Hi RBDell
Don’t take the demo mp3 files to be a good representation of the keyboards, as to save space they tend to be made at 128Kbits or less, (Anything less then 192Kbits produces total pants) and consequently all the sounds tend to sound similar between instruments, a classic case is the pre-launch demos of the Tyros 2 which to be honest would put anyone off having one, even in the smallest room of the house, (They really were that bad) but listen to it live and WOW your ears tell you this is one hell of a keyboard, (Still not the best sounding to my ears, and certainly no where near good enough to make me even think of changing my Abacus though) and it is easily understandable why people flock to purchase them.
The second thing you also have to take in to account is that if your listening to them on the typical Hi Fi Stereos that are sold in the Electrical Chains, (Or even worse these sort of systems that were available 10 years ago) then you haven’t got a cat in hells chance of hearing the capabilities of the latest Arranger Keyboards.
So before making judgements, make sure you have really heard them to there best.
Point to note: A lot of keyboards these days use recordings of a live drummer playing a real drum kit, in there styles, and you cant get any more real then that.
Also take in to account that the sound you here when you are playing on stage, is totally different to the sound that the audience hears.
However whatever you play, the most important thing is to enjoy yourselves.

Bill