I can see the cosmetic differences and understand there's a weight difference.  Are there any performance differences?  

I don't think there is any performance difference with respect to casting.  IMO, the STX does feel a wee bit smoother, thanks to the extra bearings.

Other than the weight, the major difference is the drag.  The STX has three carbon matrix drag washers.  The schematic for the Premier shows one.

Thats one thing i dont understand...The STX looks better on paper with more bearings but is $50 cheaper...Is the higher price tag for the premiere just due to the weight?

Is the higher price tag for the premiere just due to the weight?

Yep...

Yeah the Premier is a proprietary aluminum that seems to rival magnesium in lightness.

The Premier has 5 HPCR Bearings+1 Roller Bearing and the STX has 10 Stainless Steel+1 Roller Bearing.  

I own both, I like both. In my opinion the STX is the best of all the Revo's.

I own both, I like both. In my opinion the STX is the best of all the Revo's.

Wow, even after making the big Premier switch?

I bought a Premier a few weeks ago.  I kept it two days and returned it and got a 6.4:1 STX.  Then I decided I wanted to try something else and got my Johnny Morris.  I'm still a Revo loyalist, though.

The STX is the best of the line, IMO.  It feels a tad bit better than the others, even if it is heavier than the Premier.  

I own both, I like both. In my opinion the STX is the best of all the Revo's.

Wow, even after making the big Premier switch?

I didn't "switch".....I added the Premiers. I still have my STX's.  

The Premier just happens to feel like an STX on a diet.  

I've got both and they are hands down the best baitcasters I've owned in 15 years of fishing.  

I got the STX and it feels like its on a diet compared to the Curado 200D's I use.  It has worked flawlessly and its drag is extremely smooth not just strong.  I still dont consider it as nearly as strong or nice as the 200D though.  10BB's but not as smooth and a bit vague in feel comparable more to a Daiwa.  Im so anal about my reels, I keep them protected with a neoprene cover even when not in use on the boat.  Yet the STX so easily gets rash on the sideplates, again just like a Daiwa.  The textured frame is so cosmetically delicate the reel feet are burnished by the fuji's cushioned hoods on the reelseat.  The infini-spool II design does rival Daiwa and it casts incredible.

Just my opinion here of course, but....Revo > Curado