I have been generally quite pleased with these products. And with 30+ years in professional computing I am quite well aware that perfection is impossible. I maintain a system of regular backups and keep prior versions of software for the ability to rollback with ease.
Still, the very nature of registry cleaners makes use of this class of software more risky than other types of software. The statement that v540 should address the problems of V539 does not give me a warm fuzzy feeling. I expect more. Had V539 been released as a public beta, I would have no issues; however, as a released version that had errors of this sort, that apparently are not yet completely identified and known, does concern me greatly.
And yes, taking an upgrade charge and then finding out it it being offered for free does smart a little. It was apparently possible to send out emails about the upgrade, but not about the free upgrade? Although, upon further research, I find that the email address for the first of the three products purchased, RegSupreme, is an old email address that is no longer around, so it would not have been possible to be notified at that email address anyway. I thought I had notified MaceCraft of the email address changes, however.