It depends on the type of shooting you're doing, but for my personal use I think an MOA base is a waste on a rimfire. In fact, I'm really not a fan of them at all. I shoot for fun, not competition, and I'm always honing my hunting skills. I just ring steel when I shoot long distances at 500+, and don't worry about shooting extremely tight groups...at distances under 500 yards I go for "good enough for hunting accuracy," and I regularly switch between targets at varying range so I can practice where to hold rather than trying to always center my reticle, so I can get quicker shots off (which is a must for hunting). Get a good scope with hashes (whether it's MIL or just a BDC...I prefer MIL) and familiarize yourself with how the rifle shoots at various distances. You can then use the scope to learn where you need to hold to hit center, and even account for varying conditions.

This target is from my 93 in 22 WMR, zero'd at 100 yards. With a simple duplex reticle, I shot this group at 150 yards on an almost windless day, holding about an inch above zero. It'll shoot 250 holding about 4 inches above zero, though the groups open up a lot more. 17 HMR shoots even flatter than 22 WMR, so you should be able to achieve similar results relatively easily.