Just a FYI on pricing. Tib mags MSRP is only $29.99 (and thats the FS version). Many retailers are selling at old prices though, as they bought the inventory before the price drop.
The reason I Like the T8 is that I don't have to change my 12g after a few mags. I own 5 mags, and can get an easy 24 shots (3 loads) per 12g. thats 120rds with 5 mags. If you had a TPX, you would need 17 mags to get the same shot count with no reloading.
But it all boils down to preference. To me, the TPX feels like a toy I used to have when I was a kid, and I expect to see pennies fly out when I pull the trigger. I just seems like it's fragile. The T8 on the other hand is big, yes. I have big hands, not a problem. I HATE changing 12g in a game, and it makes a great marker for my needs.