Option (a) sounds good to me (but I'm biased). Get a PSR3000 - I'm not sure the Tyros extras are things you would use - and playback SMFs from the Smartmedia card. If you get a 128meg card you shouldn't run out
of space too fast. It's easy to edit midi files to suppress the lead line; also I've set the "Other tracks" button on my 2k to suppress track 4 as well, as a backup "lead mute" button!

There's and interesting midi file player available in the UK, the "OKYWeb" which uses compactflash storage. Details here: http://www.bck.co.uk/. However I suspect it is only 32 note poly.

I think this is the manufacturers web page: http://www.okyweb.com/. It's in Italian, however!