I spoke to WLMG Slough last week about the warranty. The GT-R guy (Jas) said it was going to be £2k PA but didn't have any details of the coverage. I've asked for details to be sent to me as soon as they are available.
I've also asked Litchfield to confirm their offering but they're not ready to do so yet.
I'm likely to go down the latter route as it's likely to cover their work/upgrades etc.
Of course you're absolutely right in that this is simple an insurance product. You're paying to cover a risk. In most circumstances I don't bother with post-sales cover but given the potential costs involved then I might. All depends on the price point.