It is all self reported, so you should take it with a grain of salt. THere is such a small pool of data for splitters and super splitters, that it really isn't fair to conclude anything at all. You just have to make your application perfect, and kill the LSAT. After that, it's praying to sweet baby jesus that adcoms somewhere see something promising in you.
Splitters are often more common to use consulting services like MS9 to help with the application process, so that also might be a leg up against other splitters. It obviously isn't required, but if you're looking at maximizing your outcome, it's definitely something to look into. They do amazing work.
Yeah I think the fact that it's self-reported definitely makes it appear more favorable for splitters than it actually is. I always wanted to do the consulting thing, I just don't think I can afford that cost for what might be a negligible boost.
While it's easy to see people lying and making up stats to give false hope for splitters, I think there's a case to be made for the other side as well. Since it's such a small data pool, I wonder how many overperformed but for whatever reason decided not to report their success? Maybe this is a clause with certain consulting firms? (I have no idea, entirely speculation)
As for the second statement, I don't know if I agree with calling their success marginal. They have plenty of testimonies of getting 50k+ increase in scholarships out of negotiations. Even if you pay them a few thousand (not sure of price, but let's say 2g), that's a pretty damn solid ROI if you have the cash up front (easy for me to say since I've been working full time for 2+ years).
Their staff also personally know deans, adcoms, etc from a majority of the T13. I won't go as far as saying that they will call Asha up at Yale and ask for you to personally be admitted, but I have a feeling they'd be more inclined to pick a MS9 user over a random person if it was a crapshoot between the two (identical stats). They even consult for law schools. So they obviously have great working relationships with some of these people who will be making decisions on your acceptance/denials.