I was an EMS/XMS ninja. I vaguely remember getting it as high as 610 I believe.
I never had a problem running games after I hit this one (I think it was Wing Commander 2 with speech pack) as it has some really shitty requirements to run it as far as EMS went (over 600 of 640K.) It took awhile but I figured out this slick way to pawn off some stuff and disable or change figures in the autoexec and config files where it paid off. Sure here and there something may have needed a tweak since, but that was a huge roadblock and when I broke that wall a lot of stuff I had going ran better too. You just needed to know how to mess with stacks, pages, and other goodies. I learned a lot manually messing around and at times on BBS's in the area too so I could get cool Future Crew (and others) demos to go too.
I don't miss it, it was damn fun, but I wouldn't go back either because I think the lack of speed and screwing around in dangerously old hardware likely to crap out with drive me nuts. DOSBox serves its purpose just fine.