Yeah, I use the astroflight for my LiPo, too. I got the ice to supplement during the upcoming racing season. The 5s Lipo will probably feel more powerful than your 18 cell packs, as they have a lot less weight and superior punch vs nimh packs. The top end may or may not be the same, but it will probably be close enough that you wouldn't miss the extra 2 or 3 mph. 4s Lipo feels like 14 cells. 3s Lipo feels as punchy as 12 nimh cells, but with a slightly lower top end speed.

I myself am using the 109 astroflight charger - I love mine - No problems whatsoever.... The duratraxx seems like a pretty good charger as well.

Only if my Alpha4 did Li-poly and had high Amp rate it would be that much more awesome!