I still don't use HMB for mixing (Ardour is a pain in the ass IMO), but I run all my final masters through the channel strips, and the saturation does improve the sound noticeably.
The only problem is that it does not support Rewire, so I have to use a system-wide installation of Jack which makes the whole audio setup rather instable. Every few minutes it has to be re-initialized.
Regards,
Steffen