Falcon 900 Captain reports exceeding 1500 FT during the TEB5 departure due to lack of autothrust; which the reporter has become reliant on flying the 900 Easy.

Narrative

After briefing Teterboro 5 departure we took off and exceeded the 1500 altitude restriction. I immediately reduced power and nosed the plane over to get back down to 1500 FT. The Controller did not get our initial call which was good allowing us to descend back down to 1500 FT. We reported level at 1500 FT nothing was ever said to us by ATC. We know EWR traffic over flies TEB and to our fortune there was no conflict. Events that lead to this were: I had not been in this aircraft in over 6 weeks and the co-pilot had not been in this airplane in over 90 days. We have been flying a 900 easy; which has more advanced avionics. The lack of recent experience in this aircraft help lead to our altitude bust. Upon reaching 1500 FT I was expecting the autothrottles to reduce the power. But no autothrottles. The thrust was still at takeoff setting; which lead to the aircraft flying through the assigned altitude. The day before we had a conversation with our company standards pilot expressing to him that we are becoming increasingly uncomfortable with flying the 2 different types. The avionics are so different that we feel we should be only allowed to fly one of the two types.