Maybe it's just me, but testimonials scream 'desperate' to me. I associate them with infomercials and medical quackery (usually infomercials advertising medical quackery.)
That's not to say that word of mouth isn't a good way to find things, but really I think the best advertising for C2 are the games that are made with it. I found construct after watching a video on youtube of a work in progress game... if I'd come to the scirra site afterwards and the first thing I saw was a page of "I use construct to triple my productivity" type quotes - I would have been immediately turned off.
But, as I say... it's probably just me.