I picked up one of the RopeRunners. I only have one climb, a removal, so this is all preliminary. I started with a base tie and went to a choked tie in.
Once its on the rope it functions wonderfully. In just a little use I noticed:
It offers minimal sitback.
It easily breaks 100% and immediately tends slack, friction free.
Release from suspension is smooth and easily modulated. You can scream or creep! The release, while not exactly the same as a prussic is remarkably similar and feels intuitive compared to the Unicender, ART products and other similar devices.
The 'bird' or top piece when its on rope is sensitive. It works fine with user control but if you slap it while its weighted it lets off indiscriminately. I haven't perfected the tending system, and I definitely had a little trouble getting it on the rope. It is more complicated than other devices, with more parts but it offers mid line attachment. You could always thread it like a Zig Zag and such.
It feels durable and well made and its a great size. It looks large in photos but on rope its similar in size to a hitch climber setup.