TL;DR The proposed prices are too high
Like many I've been a customer for decades, back as far as when Kirk provided support via the Rob Galbraith forums. I think it was Photomechanic 3 in those days. The best part of 20 years later and we're at version 6, so Camera Bits has had the initial purchase price and three upgrade fees from me. After all of that time PM from my perspective is basically unchanged and I have appreciated that as it hasn't broken my workflow, required me to learn new interfaces, been utterly reliable and top notch support has been there from Kirk and colleagues. The counterpoint is that because development has been so slow Camera Bits has had relatively little income from me or anyone else. If we'd been at version 15 by now the financial picture would have been different.
Now we're in the position of facing a sizeable subscription or a huge increase in the perpetual licence. Unfortunately in my view PM is too late to the table. Many if not most customers will have Creative Cloud subscriptions and be comparing value for money. My Adobe photography plan includes two alternatives to PM, Bridge and Lightroom, which are effectively 'free' with Photoshop and all for a much lower subscription. Both are capable of replacing PM for many users. Of course there are some unique features in PM which will be indispensable to some but they may well be a relatively small percentage of the customer base. For everyone else there are alternatives they're already paying for. I'd be happy with a subscription fee of 30% of the intended one and would call that fair value. Otherwise I'll be running 6 into the ground while checking in from time to time to see if genuinely useful and unique new features appear with sufficient frequency to tun my head and woo me back. In the meantime, thanks to all at Camera Bits, it's been great.