600ma might be ok, depending on the size of the plane, I'm not familar with the one you mention. However, with 5 higher power servos, you're going to see a higher drain on the pack. I have a 600mah in my Funtana, and I only get 2 10-15min flights before I pop it on the field charger. (actually, when I think about it, I recharge after every flight, it's easy to do, and no worries).

So, if you want the same kind of duration you had with a trainer-type, you'll need a bigger pack.

Oh, and I agree, for that kind of plane, you want quality servos, the best you can afford will help. If you go digital, the 600mah pack won't cut it anymore, those things really draw a LOT more power. Not because they draw more power at peak, but because they hold better and draw more power at "no stick" or small movements. (though digitals often have more powerful motors as well, upping the current draw even more).

If the plane is larger than .60 size with 5 standard BB servos (50inoz range), you should upgrade the battery.

Of course, packs are cheap. airplanes aren't.