I think I'm going to get the C-Comp porting on one of my glocks just for the heck of it.  I already have them set up the way I like, so I don't want to buy a NEW ported glock (though PSA has G17Cs for $459 at the moment w/ free shipping--thanks Plouffedaddy/gunsngear).

Anyway.  IF you were going to port either a g19 or a g17, which would you do and why?
I'm leaning towards the 17 since (a) I carry it less, and (b) the velocity loss won't matter as much as with a 19.  I also may cut this G17's grip down to 19 size (because I have more 19 mags and don't want to ever accidentally grab the G17 and an extra G19 mag--and also, I think it'll reduce the size of the hump more than the OEM 19s hump).  If so, I'd be carrying it more.  

I don't buy into all the fear about blast and noise and bright flashes killing night-vision and blocking the view, etc.   Good, low-flash ammo is abundant--and most reviewers I trust say all the fears are overblown.

Velocity loss is not really a huge concern in pistol service calibers as they tend to all preform essentially very closely or the same it would be like using a shorter barrel.

I would probably buy a barrel from Lone Wolf that was longer and had the ports external the slide if I wanted a compensated Glock.  I have shot several Glocks that were factory C models and in the 9mm I really did not notice any difference.  Had it been 10mm I think it would have been beneficial but in 9mm it just made the pistol louder.  If you ever think you may have to discharge your pistol in doors a compensated Glock is going to ring your bell trust me I shot one in a confined space before I had hearing protection and it was significantly higher sound pressure levels.

Yeah, good point about velocity.  Tons of 3.5" barrels do just fine.

I didn't expect MUCH help...may 20% flatter shooting.

The problems with the extended barrels is (a) holsters--some may work though, so I'll look into it) and (b) I like Wilson Combat barrels--though I wouldn't be averse to trying KKM.

Storm Lake makes good Glock barrels also in addition to the ones you mentioned.  Honestly ones you start comparing WC, KKM and SL it is splitting hairs.  

20% might be a stretch for 9mm since recoil is already low..... Their will be some but in my experience with them not much but this could be different with handloads or hotter rounds that do have more recoil than standard or plinking ammo.

I shoot some pretty hot stuff--lots of Winchester 127gr +P+ out of the 17 (the 19 gets mostly standard HST in 124/147).  
Thanks for the ideas--I didn't know if Storm Lake was any good, but I love my Wilson Combat barrels, and have heard pretty good things on KKM.
Thanks again.

I like my 17C.  LEO trade in from AIM for $379 (long sold out now).  I don't know that there is a real way to measure it, but there is a noticeable difference using the C barrel vs. putting a standard 17 barrel in the same gun.

I missed out on those I wanted to snag one but when I went to order it was out.  It was such a good deal on a G17 and I missed it.

Yeah, it was all the positive reports coming back from that and other TRADE-IN deals that got me wanting a C (but while I can't justify the price, I can port one of mine for $150 at rockyourglxxx).  I'm mainly just into tinkering and looking for little benefits here and there--one thing with the Gen4 is that I might want to take the spring down one pound which isn't easy to do with a DOUBLE-SPRING (which I prefer over single springs).