Either there was a temporal lapse or I found exactly one IP so far from which I could access the board... but my home IPs and those of my servers are blocked too.
I do not know the technical details but my assumption is that either someone decided to issue an overly aggressive ban on any IP subnets seen during the recent spam attack, or they made a typo when entering the ban and accidentally banned more subnets than desired. Either way, I heavily doubt the forum is "hacked". A hacker would be much more likely to do something different,e.g. embedding malware rather than annoying members by banning their IP subnets.
I'm one of the guys behind the Roland memory card project, and since it was a rather popular thread on VSE, I would like to point out that I also created a thread on Gearslutz about the project, so feel free to post here in the meantime:
Roland M-128/M-256/M-512 / Akai BR-16/BR-32 compatible multi-bank replacement cards