No and yes. If your plants are well established, then no. If your plants have a nice root system already or you put your stems down deep enough, then no. But fresh planted foreground plants like HC, HM, etc, then yes. I had a "bleep" of a time trying to plant some cardamine because the MTS would uproot them when they came to surface. I just gave up on those plants. But MTS are beneficial, so don't give up on them. I'd suggest letting your "small" plants establish themselves, then introduce the MTS.
I couldn't agree more! At least if you're planning on adding adult MTS. CMB, have you had the same problem with baby snails? I've had my HC going for a couple weeks now and added a handful of the tiny MTS I had from another tank. So far, no problems. I'm sure the larger ones would be a different story, though.
What kind of substrate do you have? I use Flourite and I have tons of MTS adults and babies in my tank. Ive had them for a year and never had a problem with plants being uprooted by them. Color Me Blue is right about the roots being established, it should be fine.