That's what I've been thinking too. In fact, the inside of my liners is probably the only duct tape-free zone anywhere on my ski gear. Just worried that the tape might work it's way off, taking some material with it and just make things worse. Need to study the liner a little.
I've been toying with various solutions for these boots (Nordica K9.1). I've got three shells, one of which is practically mint, but all the liners are fading. Talked to Nordica (which sold me a replacement liner some years back, which worked well) and they suggested a Beast replacement liner for 120 euros. If I were sure that liner would match the shell I'd probably go for it. Zipfit/Intuitions seem a bit spendy/hard to justify. Might just see if I can find some boot on sale with a similar liner.