I've heard that the second option (the t-bar mount) does not hold its position very well. You can bend it into whatever configuration, it just won't stay put.
I have the first option and have only used it a couple of times. It seems to work fine, but I have not really measured whether it will allow precise ORTF, DIN, etc. You can do XY, but the mics are not completely flat horizontally, you have to *slightly* angle one or both of the mounts to get them to cross XY. I suppose you could put some kind of spacer on one of the mounts where it attaches to the T-bar.
Hope this helps!
Oh yeah....I plan on getting full sized wond screens to go over the ends of the mounts, the tiny screens that come with the tiny mics are worhtless.