I've got 3x TV Barlow. Its great but can't use it only when seeing is very good. I use 2" Japanese Barlow much more often.
I would recommend 2" 2x TV Big Barlow, like Jeanette's. You can use it for both 1.25 and 2" eyepieces. All you do is put the 1.25 adopter that comes with all scopes in 2" Barlow and all together in the focuser
cheers