I don't see the point using Plastiq and pay the "reduced" fees of 1.99% for Visa and Amex CCs when I can do the same using Serve B/P for free. Maybe useful if one has only one prepaid account and they've already maxed out the loads and still have a bunch of bills to pay? But for those with several Serve/BB accounts, I don't see the need to pay a fee when I can get it for free and enjoy the rewards instead of passing it on to CCCs and click the bloggers link.
I see why a lot of bloggers are pushing it heavily because of the commissions they get from it. Caveat emptor.