I was going to mention that K-Array in Italy make some good quality high-excursion 2" drivers, but since AG has already pointed out that only the Chinese make them and everything the Chinese make is crap then I shan't bother.
There are some very impressive drivers of 2" and lower size. The trick is high excursion and the tradeoff is efficiency - basically they just throw power at them and use equalisation in DSP to achieve a good sound. Many of these drivers are probably run below resonance, which is unusual for a traditional hifi cabinet. In modern battery powered applications (the bluetooth speakers we've all heard) the low efficiency of the speaker (sorry.... squeaker) is probably more then made up for by the increased efficiency of using a class-D amplifier.
Externet: Is your goal maximum SPL or maximum efficiency? Are you hoping for a full-range sound or can you trade off some bass?
In all honesty, I can't offer any more practical advice than to buy some and try them out I'm afraid.