But the two have been widening slightly and I was able to get a nice clean split the other night with my 105 at 174x (3.5T6 Nagler). I then dropped in a Pentax XO 2.6 and saw a wide gap between the two.

IIRC, the A-B gap should be at or just above 1.1" (and gradually widening), so that puts it close to the Dawes Limit of my 105. At any rate, this means we should all be able to enjoy these gold beauties for many years to come!
Cheers,
Ron