Look under the hood on 7x00 and 7x10 tractors and they are not any different that 4x50 and 4x55 tractors.  Mechanical pumps, mechanical hydraulics, hydraulic engaged PTO (via solenoid valve), powerquad 16spd is robust and reliable.  If you lost the dash in a 7800 you would not know engine speed, pto speed, ground speed, fuel level, engine temp, etc but the tractor would still run and could be ran for years like that with no problems.  Guys proclaim the 50 and 55 series to be the best, but they have electronic tach, pto speed, ground speed, fuel level, engine temp, etc and a lot of tractors are used without ever looking at those screens; most every guage in a 7000 could be replaced with an aftermarket solution to display the info and the tractor would still run.  The only exemption might be the 19spd powershift that utilizes some computer controls; everything else uses electronics for feed back only.