I can lock up my HY/RDs no problem. The only learning curve is getting used to the amount of lever travel they use-- I can get the lever to about 1/4" from the bars for full lock, compared to a typical rim brake that might use 1/4 of the lever's total travel. But once you get used to it, you realize that is the strength of the TRPs-- modulation.

Not that I wouldn't like a set of those custom arms. I totally would.