[Xuzz]

I'd also be concerned that on Android that the user might have a device that doesn't allow off-Market installs, and then I'd have to use a distribution mechanism I don't prefer (maybe even an alternative market like Amazon was rumored to be creating).

No platform is perfect.

[statictype]

Less of a concern. If Apple decides to go into the Medical gadgets field and updates their terms of service accordingly, you are basically hosed. There's no recourse. Not even an alternate 'off-Market install'.

[Xuzz]

Unless your customer's Android device happens to come from AT&T, where you have the exact same issue.

(This isn't to say I don't agree with you that they shouldn't be able to kick you off, but, you know what? No mobile platform is good in that respect.)

[dejb]

Yes but your program will still work on other android platforms that don't try to prevent non-app software so the software development effort investment isn't wasted.