I have experience with the Clarity TC caps. They do involve some rethinking when it comes to mounting them. And compared to the Panasonic electrolytics they replaced, there was a significant improvement in sound quality. The trade-off is size and cost.
I hear what you're saying about stabbing in the dark. Personally, I say stab away! Kill it! There's Grues in there!
Ok, seriously; this is part of the madness and enjoyment of this hobby. Experimenting! How boring was audio when you just bought stuff and listened to it?
SO boring!
So experiment away! You never know when a change will really make a difference until you try it yourself.