I've used the pH Perfect line. Here's my experience, take it for what it's worth.
To get the "guaranteed" effect you're supposed to use the pH Perfect base nutes (Sensi 2-part, the GMB 3-part, or the Connoisseur 2-part) and then the Hobbyist bundle along with that which consists of Big Bud, Voodoo Juice, Overdrive, and B-52. That's the bare minimum for the guarantee, but of course the real pH balancing comes from the base nutrients so most everyone will see that work fine with nothing more than the base nutes. My understanding is that the Bundle is included for the guarantee because it has just enough extra stabilization capacity that certain water chemistry might not work perfectly with the base nutrients alone. What I remember of high school chemistry says that makes sense, but I'm no PhD so I can't say for sure.
Regardless of whether the reason is true or, as the nay-sayers would undoubtedly suggest, an attempt to make you buy more stuff it is worth it in my opinion. There's a real difference to be had from adding those four additives and - again, just my opinion - it more than makes up for the increase in what you're paying.
As far as the Expert and above bundles are concerned, I like them. I've done the Expert level (they build on each other, so Expert means you're getting base nutes, Hobbyist, and Expert bundles) and I am VERY pleased with the results. I'm currently running it at Professional level but it's too early to say how it is going. It looks like another significant step upward but it's still early. I haven't come across anything by AN so far I'd call a rip-off so I'm pretty confident this will be worth it.
So it's up to you I say. If you're interested definitely do the Hobbyist level, that's absolutely 100% worth it. Above that it's personal preference I say. If you're happy with the cost/reward ratio at the Hobbyist level and want to move up, go for it.
Dude that's great your 1 of the 1st that I have came across running the PH Perfect line. Tell me more. What kind of water you using? Will it work with city water? Will it hold it for 3-4 days so I could leave on a weekend and not have to worry ph running crazy?
I have to say although since Ive been using sulfuric acid for ph down a phing my water after 24hrs of bubbling, my ph is pretty rock solid lately.