You won't get any better than RTK you have. Granted if you go to the 6000 w/ RTK you have a FAR longer RTK-X period (days) before it drops out opposed to your current 15 min. But any X or float or anything isn't as accurate and you said best. 


The most accurate RTK is radio/base station with a base near the field. If you have that, you have the best. Everything else starts introducing little bits of error or possible error from cell to satellite based RTK. 

Can you get a better screen? Heck yes, the Gen 4 is far better than the 2630 and G5 stuff is even better. But we're talking like screen size, resolution, processing speed. It's not making your machine "more accurate"