There was one incident with a titanium reg. Can't remember what the percentage was, but I believe it was something like 70%.Wayward Son:The other concern on titanium regs is nitrox. Mostly, from what I've read you shouldn't use them with nitrox. I think they cna be used with under 40%, but that even with lower percentages there is a bit of a risk factor.
For me, that takes them off the table before I even look at a price tag. I find nitrox too usefull in recreational diving to buy gear that might be unusable with nitrox.
I've been using a MK25T/S600T as a primary for two years now going up to 40% and not once has it caught on fire. I dive exclusivly nitrox and last year had over 250 dives and this year I'm pushing 200 to date. I wouldn't worry about it as long as you are using for 40% or less.
Frankly I don't know that the titanium is worth the extra money and that would be the consideration for me. Since I own a total of 5 MK25/S600's and only one is titanium, you can see where I spend my $$.