I have a close friend with a Tyros 5 and have played it a lot. After seeing and hearing my Korg, and realizing all the amazing real-time controls it has, my friend sold his T5 and bought a PA4X.
Don't get me wrong, the Tyros line sounds great and has a plethora of styles.
It doesn't matter to me what model anyone else uses, I'm just relaying my own impressions.
Although I don't own or have even played a Pa4x, I own a PA3x and a T5-76, ( a great combination!!) we've been away from home the last few months I only had room in the van to transport the Pa3x, but have to say I have not missed the T5-76 one bit. ( can't believe I just wrote that).....
At least I'm thinking there could be a Pa4x in my future and then again maybe not, I'll check which way the wind is blowing tomorrow