I have used one of these on a 50cc 3d model with 6 high power digital servos and found it ( Like all powerbox equipment) To work faultlessly. After a pretty heavy session of 3d that required quite a lot from the servos the heat sink was hardly even warm to the touch.
Have you seem the Jetpower review of this product?
http://www.modellbau-deutsch.com/e/t...4Gemini_en.pdf
Well worth a read.
Regards Al
P.S They are in stock and ready to ship.