I just went through the process of replacing my T15 a few months ago..... I considered the generic replacement and the reviews left me with some concern so I bought the Hayward T15 on amazon for 420 and free shipping. So... I guess it's about $50 more.
Unfortunately the problem doesn't always end with the replacement of the cell. Apparently the mother board is stressed as the cell becomes less efficient and after replacing the salt cell most people find a week later that their system shows the message "no cell power".. In fact it is so common that there is a website nocellpower.com that is dedicated to teaching a motherboard fix that unfortunately did not work for me.
I will make one suggestion. Prior to installing your new cell get a very accurate salt reading from your pool. Chances are that as your cell deteriorated you (appropriately) added more and more salt due to the low salt indications from your system. As a result you now probably have more salt in your pool than you want. If you attach your new cell with a high salt content it will draw many amps through the board thus causing (in my opinion) board failure. So.... my recommendation is to get your salt level down to approx. 3000 before installing your new cell.. I know that it requires removing and adding large quantities of water but it's cheaper than buying a $600 circuit board.
Best of luck.

RB