I've been using a rod for frogs and have 50# PowerPro braid on it. Is there any reason this shouldn't be used for regular T-rig fishing(Besides the fact it's really difficult to fish thru a bullet weight)? I caught one on it yesterday. I suppose a leader would alleviate that problem. I just feel 15# Big Game is just as visible.

If you're fishing in heavy rocks I wouldn't use braid. Otherwise, you can use it anywhere you want. I wouldn't add a leader but you can if you want. 

I've fish a t rig on 40 and 50 lb braid with no problems.  Sometimes i like a leader just to help me with breaking off when i get jammed.  otherwise, i'll fish straight braid.  I would prefer the braid in this situation vs the stretch of the mono, but that's just my opinion.

that's what I use all the time