I tried that. I got about 1000 miles and the boot wore through the tire. I've also had grit wear through the boot.

It depends on your needs. If you want to experiment, then have at it.

If you need 100% dependability, then replace.

How are the threads? Bulging tube?
I've heard the suggestion of a glue-on radial tire patch. Perhaps a patch + filler (shoe-goo, or something else?)