Have used them, installed them, and happily sell them. Recently got a set for a Sako TRGS in 338 Laupa, with a Night Force.
Optilock rings are a great design, extremely strong, and eliminate any tube stress. A smart take off of a pillow block bearing.
Burris orginally came out with the first kind of this ring style in the Signature model.
The smart part of the Signature ring is patented ability to use inserts to adjust windage/elevation w/o affecting internal adjustments.
Sako former owner of Tikka, has made the Optilock available for both Sako, and Tikka. A larger, heavier version of the Burris Signature but w/o variable insert sizes.
Haven't had problems with the Allen style socket screw heads, do prefer Torx which will eventually be standard.
I was wrong on the price in my first post. SIR has the blue bases at 86.99 and the blue rings at 94.99. Thats over 200 with taxes. Can usually do better at Farmerssupply. Could probably set up with something else just as good for less money.