Would .17 sec. speed on a servo be good for 3D? Granted people say the faster the better, but I would like to know if I can get away with servos that have this speed. Could always go with less expo to, right? The servo's would be Hitec 625MG's or 5625MG's on 4.8 volts. I'm leaning towards the digitals to since they're only a few bucks more.

Faster is better however it really depends on what plane, what surface, etc... .17 is not a slow servo and unless your flying extreme 3D then your not going to be able to tell a difference. I wouldnt go with less expo to make up for the speed. IMHO unless you fly like quique then your not going to tell a difference between a .14 servo and a .17 servo. Go with the digital servos you will thank yourself later and run it on 6 volts it will speed them up and make them stronger besides digital servos can be voltage hogs so if you go with the digis then I suggest a 7.2V Li-ion pack regulated down to 6v and run pretty heavy gauge wires. You can get Li-ions for a reasonable price here

www.troybuiltmodels.com

I use them and I think for the money they are the best.

Those servos are great... just use a 6v pack instead of the 4.8 and you will get more torqe and speed. The 5625 on 6 volts puts out .13 sec. and there great for any 3d plane out there. Stick with NiMh if your on a budget.