Hey Realism, while i can only talk about my own experience with iblacklist, and the folks behind it, it may help quash any fears you have about the devs of this app being 'dodgy'..
I jumped on board with the 2g 1.x version early on, and one of the devs personally stayed on msn with me at every step (not sure if cool to give his name, so i won't), when i had a bug - which was the first that they'd seen, i was the first person to install iblacklist and not have summerboard lol - that was causing the good old stuck at apple logo boot problem.
Anyways, a good hour or 2 later, problem solved, and i didn't have to restore my phone. Which was an even bigger pain back then, than it is now.
As soon as i got the 3G, i bought iblacklist again, and got a new activation code in under 6 hours...just thought i'd fill you in on my dealings with iblacklist, as people are quicker to voice negative opinions that positive...and that's all good, not saying it aint' cool to let folks know the negatives, just thought i'd balance it out, and give a positive view
In short, personally, these guys are ok.