Check your PMs...
---------- Post added at 04:33 PM ---------- Previous post was at 04:24 PM ----------
I am living, breathing proof that this isn't true.
I am running the latest stock+ rom. My bootloader is unlocked and I am rooted and S-off (I used firewater first thing, no OTAs or other updates were applied). I use ISIS and Google Wallet just fine on my M8.
You have to use the "ISIS Root Bypass" Xposed module to get around the root block.
I'll give you one good reason to use ISIS. For me as a T-mobile customer, I get $1 back for every "qualified" transaction. I like to visit the vending machines at Costco which accept ISIS payments (in the Seattle area) and have many items that are $1. That's right, when I spend $1 to get a bag of Sun Chips or a Snickers bar, that $1 comes back to me so it ends up being free. Unfortunately, if you buy something that is $0.75, you don't get the $1 back. For a second there I thought I could make a quarter per transaction.
It's important to make every purchase to be a separate transaction or you will only get a total of $1 back instead of $1 for each item you purchase.
Be sure to read the fine print but experiment for yourself and see how it works out.