I hear you! I stand to play at my gigs... Still have semi-young knees at 42.
My thing with the display is how low the resolution is... It is almost 2016. With all the low cost, high resolution screens in the electronic market, you'd think the music industry would have caught up by now!
Nope, they are trailing by like 15 years when it comes to hardware... Not only screens but also CPU power, memmory bandwith, networking capabillities... Etc etc...
The hardware of a whole TOTL arranger like Tyros 5 doesnt even cost €150 for Yamaha And thats including keys, screens and buttons... Buy not assembly or software... Just the parts...