Dave,
I don't have the BA bags but I use a backpacking quilt when I have to go to ground (I use a hammock) along with an insulated pad (Exped Downmat 7) when the temps are cold (below 40F).

I typically sleep on my side and don't do a lot of tossing and turning. If you do, this may not be the bag set up for you.

I do know a couple of other SM's that use the BA bags and they love 'em.
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If you think you can, you can. If you think you can't, you can't. Either way, you're right.