I bought a 5x5 Mefferts just a little while ago from Ton. In the beginning it was quite stiff, but mine has got adjustable screws which I used to loosen it, and I'm going to lube it soon. I like it more than my EastSheen 5x5, as it is so small and pops alot.
Rama uses his Mefferts 5x5 in competition and is always very positive about it.
