Yep, I have (QSK-5). Sorry about the delayed reply, I just noticed your question.
It works, never had any problems with it. One small quirk, if you call it that: You can't use an "internal keyer" and the QSK-5 together. You must use a keyer that actually plugs into the QSK-5, and then the QSK-5 is used to key the amplifier, key the exciter, and switch the RF in the correct sequence to prevent blowing up most of your station!
73 de Steve WB2WIK/6