The only real disadvantage to the strip is that if you do flat and need to put a tube in, you have to remove the whole rim strip instead of just a valve with the tape – so you need to tape the rim anyway, just in case. But really it just makes the tyre go up easier in the first place, especially if it's a bit less than tight on the rim.
What you can do is use multiple layers of the tape to increase the diameter of the rim bed, or whatever it is just slightly.
I don't think the rubber makes any odds to the security of the bead / rim join as it's all about the shape of the rim. You'll also find that tyres come up big on Flows, so a 2.1 NN looks more like a 2.25 on a conventional rim, which is nice – slightly more internal volume I think and nicer profile.