Theres a lot of talk about this over on the Zed forum, as they came equipped with RFTs when new, and while they are great in theory, the Bridgestones they put on are hard as feck and don't do a lot for the already hard ride.
A lot of people therefore put non-RFTs on, even on the //M, and since theres no room for a spare in these love machines, a can of Tyre-Weld in the boot is de rigeur.
Experience has been mixed, ranging from people with no problems, to folk who've had tyres scrapped because the fitters say they can't clean them (sometimes credible, sometimes not), through to a couple of blokes who had alloy rims permanently damaged by whatever crud it is gets squirted in.
And on that forum its relevant; I've just bought a set of 18"' 8.5J five-spoke BMW alloys that need to take 255x35xR18 91Y tyres - in RFT form they would be close to £200 a corner for the right quality tyres....non-RFTs (and they highly recommend Falken 452s surprisingly) come in around half that, so even if a tyre does get trashed, you're still in pocket.
Problem with the RFTs is that, while you can run 50-100 miles completely deflated in safety, the likely damage to the sidewall from doing so often means they are skipped anyway. So while they certainly 'get you home' its often at a price!
Also heard plenty of other stories from people who say they've tyre-welded a punctured wheel and subsequently run it into the ground with no problems.....
So its where I'm going with the old Zed.
PS - interested to hear what the water-soluble stuff Dave refers to is??? Sounds like a good compromise....