Having flown mil heavies w/o anything other than pitch and bizjets that actually prohibit climbing at high Mach/levels in FLCH, I fail to see why VS is so much of a problem. You are FLYING the plane, pay attention. Once the VS starts getting below 1000 fpm and above 400, I just set 300-400fpm and watch the speed--if it won't hold the Mach, stop climbing and ask for lower level.
GF