The PCM piano board for the Triton is quite good. But it feels much better to play these sounds (or any piano sounds for that matter) from a weighted keyboard using a sustain pedal. If piano sounds are your thing, go for this board or find some good samples to load into the sampler.

I would look at a nice PA system (the new self powered PA's coming out look like what you're after). Something such as a nice compact Behringer, Mackie or Spirit mixer teamed up with a pair of the new Mackie HR450, RCF Art300A's or JBL EON speakers. For more bass punch add a subwoofer if you need to. There are so many good compact mixers to recommend but it all comes down to how many channels you need at once. A few choices to look at are-
MACKIE- 1604VLZ, 1402VLZ, 1202VLZ, new 1642VLZ. They have recently brought out some nice mixers for live use which have onboard master 9 band graphic EQ and effects (CFX12, CFX16, CFX20).
BEHRINGER- I own a Eurorack MX2642 which is great. Other choices include MX2004 (I like this one!), MX2802, MX1604 and they are also bringing out a fully featured live/recording desk (rackmount) with built in effects which I don't know the model number.
SPIRIT- Spirit Folio (I own an older 12/2 desk in it is super clean!). Folio SX, Folio FX16, Folio FX8.
YAMAHA- MX12/4.

There are also heaps of others!

The Trinity filters featured lowpass, highpass, bandpass and band reject modes (all with resonance) whereas the Tritons filters have lowpass and highpass modes only (highpass mode without resonance). The Tritons LFO's can sync to MIDI clock and there are more waveform choices. It also seems to me that there are more modulation destinations in the Triton than in the Trinity.

Yes I did sometimes run out of polyphony when in combination mode on the Trinity and for me personally the extra polyphony of the Triton makes a BIG difference. However, lets just say that you don't need 62 notes of polyphony for everything you do so you might just be happy with the 32 note limit. The lower polyphony shouldn't put anyone looking at buying a Trinity off as this board will become a classic one day!!!!!!