The issue I seem to remember with the later Tandys were they cost a shitload and their latest model that I remember looking at at the time still had CGA so you had to do a EGA upgrade on it right out of the box. Was that the T1000 (Cyberdyne model)

Funny you have MFMs around, I made a living off of converting MFM's to RLL's, can't remember how many st-225's I converted to st-238's. I remember having to goto Ms-dos from cpm for games on my Zenith 5150 back then. I'd love to have that old system now just for the gold recovery, That whole board was gold including all the trace lines!
yup still have my ST225 that i bought a RLL controller card for (came with a MFM controller).. took the ST-225 in MFM mode from 20mb to 30 mb in RLL mode or something like that. presto instant 30% increase.
had an paradise EGA card in my IBM XT, kinda funny the card had 1 meg memory and the computer itself only had 640k. (going from memory on some of those numbers) but yeah AST 6 pack card for expanded memory and persistent time/date, an original soundblaster with 4 watts speaker level outputs and a rotary volume control in the slot plate, no amp needed.
some of the best games i can remember were on that IBM XT and later an AT. wing commander, mech warrior II.. man until doom and later GL quake nothing could touch those early games for me.