Well this is probably a dumb question but I'm going to ask anyway. I just picked up a Savage 10 that came with a 0 moa base. I was going to order a 20 moa base for it, but then I began debating myself and thought I’d bring the question here.

Most scopes (or at least a large percent of them) have some type of mil dot or bdc reticle these days. If you were never planning to shoot past 800 or 1K, wouldn’t utilizing the reticle sort of eliminate the need for the extra 20 moa from a slanted base?

If you won't ever shoot past 800 it really doesn't add much benefit to the rig, but it doesn't hurt anything either.   It is still nice to have even shooting to 1000 as you are more centered in the optic at longer ranges.  

BDC reticles are garbage, and with a mil or moa reticle dialing still tends to be more accurate than holding.  Even on a 308 most good scopes can still dial to 1000.  

Thanks, that was kind of my thinking, I guess better to just get a 20 moa base even if I never need it...it can't hurt. My shooting so far has been limited to 500-600 yards, at those distances using the reticle has worked pretty well so far. But I also understand that the trajectory is dropping pretty quickly after that, so I wasn't sure if it made using the reticle much trickier past 600 or if it is bad practice to do so.

The cant of the scope base will not influence the BDC reticle. Changing scope base cant re positions the reticle in the tube allowing the user to maximize internal adjustment.

BDC reticles certainly have their place, such as quick engagements on large targets (3 gun, combat, or hunting)

Dialing is a preferred method although it is a bit slower than holding. Most of the time, holding with a mil/moa reticle is going to be more accurate than dialing. Turrets often have errors, most are very small and negligible but some have large errors that can cause a miss or wounding of an animal.

Bottom line, get a 20 moa base if you plan to be dialing beyond 750 yds.

IMHO, you are talking two different applications.    If it was me, I would use a BDC for quick target acquisition of large targets up to 500-600 yards.   And you must know the BDC hash marks align with the ballistic drop data for your particular cartridge in your rifle.   The muzzle velocity is the variable to watch in this application.

A 20MOA scope base would only come into play if you are dealing with long range (1k yard) precision and your scope turret doesn't have enough travel to elevate to that distance.    A .308 typically takes about 30 moa for 1,000 yards.    If your scope turret has less that 60 moa  of elevation total  travel, you probably won't make it.    Scopes like the SWFA SS 10x42 have over 100 moa total travel so a 20 moa base isn't really needed for that range.

Err, no.

A 175 SMK launched at 2650 fps has 40 MoA of drop to 1000 yards.
But
A 155 TMK launched at 2950 fps has 30 MoA of drop to 1000 yards.

So, back to the original question:: If you shoot the light weight high BC bullets you can get buy without a sloped base
But DON'T there is no reason not to have a sloped base and some time you will need it.