Seven years is a GOOD life.
In some respects filter elements, i feel, are only as good as how they are treated. It sounds like you got that dialed. Check the prices between the two and see if you want to give them a try.
If Unicell didn't perform as well as, or better than stock, I don't think they would have lasted as long as an acceptable alternative.
I see Unicell, Pleatco and Filbur all over the web, but cannot seem to find a genuine Hayward cartridge to price check(#CX570XRE 75 sq-ft surface). Do you know of a source where I can buy online? Thanks