Speaking from experience with the TA/EM/PG, I tried a mix at 10% plus my homemade menthol drops and it was grotesque.
Most will disagree but the combination of TA/PG/EM tastes nothing like tobacco to me, and is completely useless as a base. I've gotten the best milage out of the TA blend by adding a drop of it per about 5 mls of base, it adds a *slightly* tobacco-ish but more sweet pipe tobacco kind of vibe. The sweet EM is very pronounced to me, and more than this and I yack.
And the issue is, if you want a good menthol vape, you first need a solid and robust tobacco base, and then about a drop of menthol per ml of base or less. Unless you're going for more of a 'candy' type menthol, which is a different rant...
I have so far been frustrated in my attempts. I've found what I consider to be a good starting point for some tobacco bases thanks to help on this forum more than anything, but everytime I mentholize, it becomes something else. not always bad, but not right. Contrast this to when I mentholize vendor bought tobaccos, and its great.
and as a former menthol smoker who only liked american spirit menthols and marlboro menthols (hated lights and every other brand/variation, all crap),
...it sucks
But the only way to know is try! I'd recommend getting the straight TA and dilute it yourself.