They can feel so crappy with high calcium and high phosphorus we avoid it. High Ca cascades to multiple organ/glandular involvement, tight spasming muscles, as Ca triggers muscle contraction, and leads to higher pain.
Rory's internal med vet gave Epakitin the thumbs up when her calcium fell back into the normal range (she's been on Epakitin since beginning treatment, even when cal was high- an oversight on regular vet's part!), so I think it could be worth considering if a cat has normal calcium levels. It's highly palatable and doesn't have the same toxicity risks that come with AH use. Binders are a PITA...seems like they've all got pros and cons.
A newer one that looks interesting is Lanthanum Carbonate. Here's a page all about binders for the OP: http://www.felinecrf.org/phosphorus_binders.htm
Aluminum hydroxide, while administering a metal and hydrogen/oxygen is introducing something foreign systemically, is better long term for all my renal patients. They didn't die of aluminum hydroxide; most didn't even die of renal failure. They died of cancer, or introducing a new contraindicated drug at home, a toxicity due to dietary indiscretion, or stopping a medication accidentally, during a stressful event or boarding/petsitting.
I'll look up lanthanum carbonate, but we have stuck to AlHO, despite Vetoquinol producing Epakitin, what would be a great product if the insect exoskeletons, chitin, was combined with aluminum hydroxide powder rather than calcium carbonate. Many internists, oncologists, and AAFP's with which I've worked and utilized for my own are pro-AlHO. Especially if the patient has a history of ever having or currently having elevated ionized calcium. No calcitriol, no calcium carbonate.
I've pulled Vetoquinol sales reps and vets that come to cater to my clinics, providing Lunch and Learns, to tease them into lobbying for manufacturing a non-calcium product. They just nod a lot, yeah, I know what you mean, just clinically with what you see and biochemically with the blood evidence, we're working on that. Kind of like when I bugged Merial about when they were gonna invest in the studies and titers to prove their canarypox live vector rabies vaccination lasts at least 3 years, if not 5, in the domestic cat immune system. They pushed that and sold more vaccines for at least 10 years after initial FDA approval for the 1 year Purevax. Booger. Bugger. Ah, hell, both ;]