If you buy a synth, the extra sounds that you will never use will always be there....then on the other hand if you buy just a "stage piano", the sounds are usually restricted to piano, electric piano, and maybe some strings...If you want a sequencer, i dont think there are that many stage pianos with a sequencer. Its usually a feature in synths
Anyway, for accoustic type sounds such as pianos, strings, brass and such, I would look in the yamaha line. The motif es series keyboards have hammer action, a sequencer, and good accoustic type sounds...they come in 88, 76, 61 key variety....Also the pricerange is in the ballpark
I have and have used a Kurzweil sp88 stage piano for a church setting. It sounds good but is limited in sounds and only has 32...piano, strings, electric piano and some organ sounds...no sequencer but does the job