sleep fm would be better if they made a decent video (browser area only), removed the stylesheet (the interface is horrible) and lost the sleep fm 'loves you' type impression. Its a utility.
It could be useful if they streamlined it and marketed it without the corn :P
I don't run my own installation (used the hosted one for about a year) but have seen friends upgrades go not so smoothly. In keeping with various updates I'd say it'd take a bit of time.
The only time I've had problems upgrading was when, running off the trunk svn build, a new tags system which changed a bunch of database tables was introduced and then scrapped shortly afterwards. Repairing the tables was annoying, but that's life on trunk for you; there's a reason it's not recommended for production sites. Other than that, all of my upgrades have gone smoothly. In my (anecdotal) experience, most problems with upgrades (and, indeed, most problems generally) are caused by badly written or incompatible plugins.
I'd never actually checked this out until this post :)
Had a look and I'm very impressed!
I'm putting together a personal blog and thought it'd be a good idea to do the posts by email - was a bit unsure on the anti spoofing measures though. I'm sure you have it sorted!
I've recommended it to a friend already- Well done!
I like the pipes idea alot though, can see it's use.