if you're seriously considering analog summing, you owe it to yourself to check out airwindows console (and airwindows dark for that matter). unless you're AAX only. the man has no marketing behind him which is why you may not be aware that this is totally unlike other console emulation plugins, which are just ITB saturators. OTB summing will sound even better, no doubt, but to me console is a step in that direction, coming from plain digital summing.
the versions i like the most are console6 (depth with extra thump) and console7 (max depth and detail, no extra thump). all versions of console are primarily about depth/3D, console6 included. but compared to the other versions, console6 has a thump to it that I quite like. it's also lowest on CPU.