It's good to have your view on this, but I honestly think you should make some reference to the MAS on your site - even if it's on a page that highlights the user downside (slower releases etc) - if I browse an app site/page and it doesn't mention the MAS I assume they're not on it.
Probably, yes. Thanks for your feedback anyways! There is a (not so visible) doc page about the differences: https://luckymarmot.com/paw/doc/Difference_MAS_Retail
I'm the founder of Paw, and frankly I like the MAS. It gave Paw a lot of visibility without us taking any financial risk. Otherwise, we would have needed to pay for some kind of advertising when we didn't have the money for it. MAS allowed us to bootstrap and gain users.
Sure, the 30% split for Apple sounds like a lot, and it surely is. That's exacly why we encourage users to get Paw from our website (which uses Stripe for CC processing). Also, website purchases get updates a little faster, as it doesn't rely on Apple's approval (which is IMO the real pain point of the MAS).
Lastly, sandboxing isn't an issue at all for us. And the version distributed through the website is also sandboxed. I personally love sandboxing, as a user first, and as a developer too. Sure, some apps (due to their nature) can't work with sandboxing, and should probably be allowed on the MAS as a special exception (the example I have in mind is the excellent Git Tower).