I ended up deciding that it wasn't going to be cost effective to try to rent (4 hours at $40, 1 day at $80). I figured there's no way I'd get it done in 4 hours and then you're close enough to a unit you own. That excludes the ethical factor of if you should or shouldn't beat on a rental.

I ended up getting a Champion unit with host kit for $240 plus a 4 year warrant. I wish I had known about the harbor freight cheapy but it's not a huge deal. I figured like you mention, I'll find lots of uses for it.

It did work out for the Alum application. Whether or not the alum application worked is another issue.

At the end I noticed that it took a long time to run that thing clean. I don't know if that's part of the problem with the things going bad or not.