Well this may be confusing, but I'm going to try to explain this. The Mazda OEM apex seals are strong & handle abuse. The Atkins seal I have heard are not as durable as the OEM thus the price difference. The cryo process makes their seals better then the non cryo seals they offer.
Now for the part that may be confusing. Some seals will be harder & take more to break them then others, but when the do break they do more damage to the housings then the softer seals. So it may come as a trade off.
From comments of others that I know the Mazda 2 pc OEM seals are very nice for low to high power cars. Your build will determine which seals to run. There are a lot of different seals offered, ceramic seals tend to be a good choice if you have the money.
Here are a few, but there are far more to chose from
ALS seals:
http://www.alsrotary.com/Home_Page.php
NRS seals:
http://www.nrsrotorsports.com/index.html
Goopy seals:
http://goopyperformance.com/
REC seals:
http://www.rotaryengine.com/products/apexseals.htm
RA seals:
http://www.rotaryaviation.com/
Atkins seals:
http://atkinsrotary.com/store/catalog/index.html