I am not impressed with their stuff for the most part. Not any better than most other manufacturers. Their 66M1-50 blocks are very flimsy. Suttle products seem to be much better, and since most telcos buy their products, I let them be the Guinea Pigs. Adherence to the original Bell specs are still maintained with Suttle, but not with most other manufacturers. I don't mind paying a little more for quality and I've found that Siemon is on the low end with that regard.
Oh, and just for clarification:
Siemon is the manufacturer of jacks, blocks, patch panels, etc., located in Connecticut.
Siemens is the worldwide manufacturer of systems, components and electrical hardware.
Sorry, but when I see "Siemons", it is like nails on a chalkboard to me.
Well, we all know me with regard to detail, don't we?