I have unfortunately not been able to do too much with my Megrez 90 lately, however it is very nice eye candy

.
I had no luck with the WO Flat III with it, due to heavy astigmatism in the corners, and ended up getting the Borg 0.85 DG-L. It has given me very flat images without any sign of astigmatism. However, this cost me 50% of the price of the scope, so keep that in mind.
Construction, finish, and tolerances all seem very good to me. If you do end up using the WO Flat III with it, you just need to throw out the outer 1/4 of the frame on a DSLR.
If you want to stop by some time and have a look, you are welcome to.
Regards,
Eric