32K!
You're very privileged getting to help Uwe Sieber with UMBPCI. It's the last DOS memory utility still under development and my favourite for XMS and memory extenders.
I watch its progress with interest since the last/fastest chipsets it fully supports will probably be the point where DOS legacy support effectively ends on the PC. And that's the point where I keep a second system for DOS (and glide) compatibility!
I've levelled off the performance of my memory managers with EMS/Page Frame and all drivers loaded. I decided I'd use SHSUCDX.EXE instead of MSCDEX.EXE where necessary and now I've got-
QEMM 629K
386MAX 627K
Netroom 624K
EMM386 623K
Coincidentally, if these were scores, this is about how I'd rate the programs overall for ease of use, interface and configurability. It's also about what level they were developed to. I have a particular soft spot for 386MAX (and, since no one else will read this, I'll tell you that if you were to send a polite begging email to the webmaster
www.qualitas.com he will probably send you a link to a legitimate copy of the final version of the program!). Notice too, when compared to my earlier "scores", that it's the Microsoft environment that benefits most from the substitution of Microsoft's own CD-ROM extensions with something third-party!