I've done thousands on my RCBS Jr., but I've been considering trying it on my 550.  Here's what I do now, and what I have plans for:

Now I do the following on a RCBS Jr. press:
Size/deprime
Tumble to delube
Trim, debur, chamfer
Clear flash hole of media if needed
Remove crimp if needed
Prime with a RCBS handheld primer
Charge with a Uniflow (Which gives me excellent consistency)
Seat a bullet

My plans with a 550 would be:
Process brass as before either on the single stage or 550 using only the sizing die, this way I would not have to pull the case out of the single stage with each stroke of the press.
Prime in station one
Charge in station two
Seat in three
Leave four empty or possibly use a Lee FCD (Haven't decided yet, but its ten bucks and not like it will take any more work)

I've found that the most time consuming part is really processing the brass.  Anyone else do something similar?  Any suggestions?  Are you happy with the powder charge consistency with ball powders on the 550?  Keep in mind that I already have a size die and seat die and don't intend on buying Dillon dies.

My process for the 550B is very close to your proposed plans. However, you implied that if you sized and de-primed using the 550, you wouldn't have to pull the brass out after each stroke. This would only be true if your plan is to continue the process with brass you're sure is not too long or needed the primer pocket de-crimped, or if the other dies were not in the toolhead.

If you planned to measure, trim, deburr, decrimp, etc. after you size / deprime, you'll still have to either: pull the brass out after each stroke or continue cycling with no other dies in the toolhead to the point they self-eject. Then you'd have to re-set the other dies when time comes to begin loading. That seems to be a bit more troublesome to me.

For what it's worth, I make full use of station 4 with a Lee FCD.

What kind of ammo are you putting together?  Is this blasting / practice ammo, target ammo, hunting ammo, or what?  How many rounds do you do at one time?

IMHO for most everyday ammo, you don't need to trim every time.  I'd trim a batch to the same OAL length, then measure occasionally, and trim it all again if they're getting too long.  

You also don't need to remove the crimp every time - just the first time on a new batch of military ammo.

If it were me, I'd deprime / size the whole batch on the single-stage, tumble it all, then finish the loading process on the 550.

What kind of ammo are you putting together? Is this blasting  / practice ammo, target ammo, hunting ammo, or what? How many rounds do you do at one time? 1000                                               [span style='color: blue;']
                                                                                   
IMHO for most everyday ammo, you don't need to trim every time. I'd trim a batch to the same OAL length, then measure occasionally, and trim it all again if they're getting too long. [span style='color: blue;']I only trim as needed.

You also don't need to remove the crimp every time - just the first time on a new batch of military ammo.  This

If it were me, I'd deprime / size the whole batch on the single-stage, tumble it all, then finish the loading process on the 550.

If you're loading blasting ammo, do use the dillon measure, just don't run max charges so as to give you a little buffer room.  check the occasional powder throw on the scale and every cartridge that recieves a throw that doesn't feel just right.  

I load55 Hornady FMJ's and  my 69 SMK's on mine.  Ball powder.

You really need to know whether they need trimming , or not.  Resize a few and measure them (10 should tell the tale).  If it is even close - trim.

Assuming you don't need to trim:

1.  Tumble brass to clean - usually at least an hour

2.  Dillon spray lube.

3.  Size/prime (station 1)

4.  Throw powder (station 2) - TAC is great for this.  Check a few throws as you go along.

5.  Seat bullet (station 3) - 2.235 - 2.245" OAL.  Check a few rounds for OAL, every now and then.

6.  Crimp (station 4) - entirely optional

7.  Tumble to remove lube - 5-10 minutes is enough

8.  Box 'em up WITH LABELS - date reloaded, powder type/charge wt, bullet type/wt, primer type, approximate number of reloads on these cases.

This process generates hundreds of top-quality rounds per hour.  The label is important.  I box mine into MTM cases with the primer facing Up.  I visually inspect every primer for depth, damage, etc.

I'm doing my .223 blasting ammo just as you proposed.  I size on a single stage and do what ever brass prep is required.  Then prime, drop powder, seat bullet and lightly crimp on the 550.  I don't crimp anything but blasting ammo.  But, I did put a Lee FCD in station four just to make sure I don't get a bullet pushed back into the case.  Don't know that it is necessary, but I do it.

I use ball powders with the Dillon.  Recently polished the inside bottom of the hopper with 400 grit wet/dry paper. Also reamed and polished the powder funnel.  The last two batches I ran, one with DP73 the other with WC846, did really well on consistency.  Now, I don't load .223 nearly as fast as I do pistol ammo on the Dillon.  I try to be nice and smooth and consistent with the handle operation. Pause just a second at the bottom of the stroke to let the powder all drop into the case.

When I first put powder in the hopper, I tap the hopper 20-30 times with my hand to settle the powder. Then drop 15-20 charges before I  begin to check the weight and make adjustments.  I wrap a dryer sheet around the hopper and hold it with a rubber band.  But, leave a space so you can see the powder level in the hopper. It may take awhile to develope "the art".   Loading blasting ammo 1 1/2 grains or so below max, you may not need to be within 1/10 grain on every throw.


Edit for spelling.

Just read the 4 part Tutorial on "loading 223" on a 550.

Link from the top of the page.