High Yan !!
Maybe include the older autofocus enlarger DA900 and DA600 in your search.
It’s negative carrier AUTONEG does fit in the M700/M800 too. This is a very fine crafted piece of opt mechanics… It do have AN glass at the upper side, normal glass at the downside, very precise masking bands and do allow formats from 135mm film (or smaller) up to 6,5 x 9 cm.
This one is much more sophisticated than the original carrier SETONEG for the M700/M800 enlargers, go and look for it!
There are two more variants, DANEG for 135mm only film with fixed mask, and a carrier called DUONEG with interchangeable masks up to 6x6 cm.
If you want to enlarge larger formats the AUTONEG is the right carrier for you, I’ve used this one exclusively in the M700/M800, it does fit for sure !!
Regards from Germany,