One of the BBB sales points is that if it cracks, you can peel back the sand, tamp it down to level and reapply the polymer. They could probably give most stones in use a million year guarantee when you think about it.
The liners don't preclude any bunker style, they were created to support the very steep ones by holding sand up top a little better. However, sand still washes if you allow tons of overland drainage to come over the top of your bunker via poor design or construction. I have measured banks that hold up, and still think that the last foot of the bunker might be 33% slope, and 25% slope (about the angle of repose on many sands) looks and holds up best.
I do think the rough surface of BBB holds sand better than most fabric liners, although there is a new generation of those.
Bunker liners might be a questionable thing here, but my sense is that within the industry they have morphed from luxury items to standard construction procedure, even with some uncertainty to life span due to their newness.