What ensoniq keyboards are capable of playing sd-1 sounds and sequences...Any insight will be greatly appreciated.... thank you

The SD1 and SD1 32-voice are considered part of the VFX family, along with the VFX , VFX/SD, and VFX/SD II. They have compatible filesizes, and though their sound sets differ somewhat between models, a piano sound on one will be a piano sound on another, and so forth. The sequencer is RAM based, at least in the case of the SD1, so it can be updated to the latest version, 4.10 I think.
Someone correct me if I'm wrong but soundfiles traded outside this family won't work because the file size and details of the parameters will be wrong. Sequences MAY work in terms of notes but you'd have to set up something to convert the sound addresses to get the right instruments. Also are disk formats slightly different? Don't know! Your best bet would be to send sequences from one machine to the other by sysex and see if you can adjust the receiving machine to make the right sounds.If anyone can make this less confusing feel free.mn

Mike Nelson is quite correct that the voice architecture of the VFX family is unique. The reason, incidentally, is that the VFX series reserve 2 of the six slots used for timbres for an optional tuning table. Thus, the tuning of the synth is also stored with the information about the timbre. This makes it very difficult even to conceptually transfer from the VFX to some other synth, since you can't be sure whether some of the data in the patch setup is a tuning table or infromation to set the timbre.
An addendum:
Rubber Chicken sells software that is supposed to take VFX sequences and turn them into standard midi files. You can find more info at www.chickensys.com
Rubber Chicken is also an excellent source for Ensoniq patches, editors, etc. (I don't work for 'em and have no financial interest in 'em, but have looked over their website. It's got an awesome set of Ensoniq editor software and EPS/ASR-X samples.)
On a much sadder note, the rumors have been circulating that Ensoniq itself is pretty much going out of the music-instrument manufacturing biz. We all suspected as much when they fired their entire R&D staff 3 years ago, and it looks as though this is the last gasp.
Does anyone know if this is true or not? If so, it's a sad day. Ensoniq produced some of the best synths around for nigh on 15 years.

You've got the right idea about the tuning tables; but the story with the VFX family, and the TSs, about this is, you've got the option of setting aside Voices 5 and 6 for substitution of a custom tuning table or a drum map.(wait, with the TSs it's a wavelist or a drum map - there is memory outside the program for user tuning tables). A program so altered is marked by a certain byte value in a certain place, so you can transport or store the program with its added parts. Still the problem of incompatibility between families remains.

As for Ensoniq's corporate mission, it looks like since the merger with E-mu and the unfortunate fizzling of Fizmo, Ensoniq has narrowed its focus to soundcards and editing tools. Anyone seen closeouts on Fizmo?mn

I've seen FIZMOs at Mars used for around $500..A frind got on from Musician's Friend for $450 through the website.