The websites you mention in your post don't actually seem to be anything about the Toppy; I don't recall the review of it in Home Cinema Choice mentioning crashes due to heat; knowing what I do of the pressures of reviewing in magazines, I'd rather suspect they wouldn't have had long enough to play with it to determine that in any case.
Certainly, if there were major issues with the box locking up due to being hot, I think we'd see an awful lot of posts on Toppy.org.uk; but we don't. Certainly, some people feel that it gets warm, but locking up as a result is extremely uncommon.
There may, of course, be other causes of lock-ups, though they're pretty rare on the Toppy anyway. If you get a lock-up when the box is warm, it doesn't necessarily follow that that's the reason why.
As I said, with beta firmwares, lots of odd TAPs, and Toppy that's often running continuously for weeks on end, I don't get lock-ups. About the only time I do get anything odd happening is when I'm trying new TAPs, or deliberately stressing the machine in some parts of the test scheme that we use to verify the stability of firmwares.
Nigel.