Thanks for the replies guys. I didn't read about those problems on other places and wasn't aware of that, but it's good to know and completely understandable that people were hesitant to buy from them again. Certainly something to check before making a purchase and I do believe that any reasonable person who wants to stay in business would take corrective steps to prevent a product from leaving the shop with similar problems in the future, which I believe they did.
Nonetheless, it makes me nervous and still want to take a rear tire to the shop to check the alignment before purchasing.
Out of curiosity, I wonder what lead to the problem. Sloppy welding, inaccurate measurements, a faulty design...
Anyway, I'm not trying to promote or badmouth any company.
This might be a bit late, but 6/4 titanium is stiffer than 3/2 but more brittle so all things being equal, it seems that 6/4 will crack earlier when exposed to the same forces as 3/2. Considering how strong titanium is anyway, you just have to think if you are going to stress the frame in excess of that point. In a crash other factors are going to have an equal or more effect on frame survivability. I can say that if I were big enough to need a size 61 then I would probably get a 3/2 frame for piece of mind.
OP, did you buy it?