The Pro II ex prints almost 4x faster in ANY mode then the 500 , in terms of digital printing , time is money. So at a 1/2 or a 1/4 of the price of a new PRO II 540 EX , its worthwhile. at 80% of the price , it’s NOT a worthy contender.
Apart from that fact , the 540 Pro II was designed for solvent based printing (there are sockets for heaters on the motherboard) , the heater/solvent setup on the 500 is very much a retrofit – the 500 was NOT designed to take a heated platten.
Splash of color did modded 500’s etc. Look at their website , specifically under spare parts (I think its under support) and you will see pumps , dampers , capping stations and heads – thats NOT a good sign in my book!!!! – IE my intimation is that these expensive parts are treated as consumables!!
What price is this machine going for? compare the HP/leasing costs etc to a brand new state of the art machine.