Haven't grown Radar Love specifically but other tanguticas such as the species and Helios did either sucker and send runners out from the main plant (Helios) or did seed themselves about (tangutica the species) in the garden. Plants will react differently in different gardening zones and situations (see the recent thread on the invasiveness of clematis terniflora) so no one will be able to tell you specifically about them in your zone 5.

As to their hardiness ratings, that is normally not well known either with any certainty. I would think that with adequate mulch Radar Love should be okay in your zone but again conditions vary so much in any one give growing zone that experience is going to be your best advice.

By the way, Kermesina is a clematis that is generaly not mentioned or grown that much in my experience. I have it and like it a lot.

Personally I would not plant Radar Love. I had it and finally shovel pruned it as was just a mess of vines with very few flowers.I think Kermesina would be a good choice. I saw it last summer in one of the stores and if I remember correctly it was sold by the time I got back.
If you can find one my all time favorite is Betty Corning. It's a real blooming machine.

I love "Kermesina"