The reviews of the Mono Gaps here on eham seem decent.
That might be your best indicator - it appears that some operators have had some luck running more than 1 band on them, as stated in the reviews. I'm sure if you got one it would work fine for the designed band & maybe more.
Keep in mind with a Hustler 4-Btv - you can ground mount it & put as many radials as you want - if you only want 3 - just put 3.
Also this antenna is easy to mods for 12 & 17m - & both would be a full 1/4wave.
I had a Hustler 4BTV with 32 ground radials modified it for 12 & 17M - so had 10M/12M/15/17/20 &40M - total cost antenna with 12/17 modification & radials = Less than $160.
Keep in mind ground mounted, you can use radials where & lengths that fit your situation.
If you get a Mono Gap for what ever reason - "they look cool"
- it will work fine.
73 K1WJ David