You're right to do that. If one factoring in the cost of making a WExx11 mag reliable (i.e. release valve replacement), it comes to about the same price as a TMxx11 mag. With WE1911, you don't have a choice to use TM mags. But with WE2011, you really should, unless you're just sticking with CO2 mags. Heck, even in that case, it'd probably be a good idea to replace the valve with TM. I think WE CO2 mags use the same valve as the propane mags.
"The Bird of Hermes is My Name, Eating My Wings to Make Me Tame."