Great! I'm glad that you intend to try it out.

The possible problem with allowing 6 max level spells to be cast per day is the same as the warlock - they could blow it all on one climactic combat instead of throughout the adventure. Refreshing after a short rest forces a character to cast spells throughout the adventuring day.

It comes down to this: how much do you trust your DM to follow, on average, the DMG's recommendation for short rests? It may be worth having a conversation with your DM about it before you play.

If you would like to convert this into a version that involves long rests, then simply graft a half-caster progression onto it. I find this less aesthetic, but it is just as mechanically sound and balanced.

Oh, and if you are entertained by this base class, here is it counterpart: http://www.giantitp.com/forums/showt...ht=astromancer