I think all the points about IP reputation impact are well taken, but as someone who had to deal with the RIRs at an ISP before and who now works at a firm that buys blocks, I would 10x rather operate in today's environment than in the old RIR environment. It's transparent and predictable by comparison.

I never had much faith in reputation to begin with, and the residential block issue is muddied by the fact that large-scale residential proxies already make that an unreliable abuse check.