Hi Ron,

"... By the off chance a higher value than 300 would help, I
changed line 49 to 350 and bingo!!! Now both the 'LX200' and
'ASCOM' settings successfully control the MI-250 mount."

That's a little odd, in that the line 49 delay time setting
ought to have no effect whatsoever on ASCOM. I'd start to
suspect that something else changed between "it doesn't work"
and "hey, now it does work". Any thoughts? Maybe the scope
got power cycled, or something else was going on in the PC,
or... ?

"...I think I will do some experimentation and change the
guide.dat and startup.mar files to include the settings for the
sky tracker just to see if the combination of the two will now
live together peacefully."

I can think of no good reason that they would not. But it
seems unlikely that anyone has tried it before, so you'll be
a pioneer. And the old saw about "you can always tell the
poineers; they're the ones with arrows sticking out of them"
may apply. But if so, I don't think they'll be tough arrows
to remove.

-- Bill