I'm sure the lens will be excellent, when used normally. I would hesitate to reverse such a big heavy lens from a handling point of view, and highly corrected lenses don't always perform well when used outside their normal design envelope. If you want a lens for high magnification work I am sure there are better alternatives which are easier to manage.
Note, reproduction ratio is 1:4.6, so not as good as the AIS 28/2.8 which gets to 1:3.9 in a much smaller package.
Very true, the lil 28 AI-S is a die-hard companion, and a joy to carry, because you can't feel the weight.
However, for studio reversals, if I would get a high-mag, Apo-like lens, that would surely be a bonus.
Usually 20-28mm lenses are ideal, because they reverse at 2-4x, and have small enough front elements to adapt (with or without stepdowns).
I am afraid, just by eyeballing this new gem, that its front
glass (forget the filter) is going to exceed the 42mm diameter opening of the BR-2A.
Hope I am wrong though ...