Crazy Eddie wrote:
Seems perfectly plausible to me
I don't think so. Mr Scott's Guide...
is unofficial. All 'more-or-less official' books after TNG said that transwarp was a failure.
Something had to have changed because TNG warp was much faster than TOS warp. Warp 10 is infinite velocity in TNG, we saw the TOS ship move beyond warp 10 multiple times.
Perhaps transwarp was a success and the books simply got it wrong?