I don't like B1, it is overstimulating too me - it has a strong 'push' feeling - the type that MDAI lacks, M1 has some of, 4-FA also some, and MDMA more... but I don't think this stimulating push is balanced by very good empathogenic effects. Instead it is easy to get overstimulated or get disproportionate residual stimulation IME.
But...I have considered it a proper option for piggybacking or using it as a primer. By that I mean to serve as a primer that provides the push, while another drug like 2C-B is added that has very little push of itself and is very easygoing. 2C-B let's you ignore it's effects compared to many other drugs. With B1 there is a flow going and it changes the whole nature of it.
Since I placed MDAI on the other end of the push-spectrum when it comes to empathogen/entactogen/stimulants it in some way makes sense to try combining them - in fact I think I once tried that and it was more or less fine (not sure if I'd call it special or particularly worth repeating or worth the risks). About risks: I mean here that MDAI should not really be mixed by dopamine releasers according to studies.
M-butylone or dibutylone etc seem like a more dirty and even less worthwhile version (and a prodrug) of B1.
And I really don't have very high hopes for pentylone.