I've had my 4500 for around 11 years, and have only once replaced the power curly cord.
Have even had rain on the rear plate dripping out through the front
Yeah: stupid me, but no issues.
What a bloody ripper machine!
I can detect easily 8+ hours on one battery, although these days I'm slowing down
It holds its own against an SDC - except on minute gold which I don't want to dig for.
Depending on where you detect, the "Fine Gold" timings may be advantageous on the 5000, but almost every where I've been with mates with the 5000 in the GT, they always use "Enhanced" like me, and not "Fine Gold". The GT ground is just too hot!
My "goto" coil is the Evo 14*9 which is an absolute gold magnet and great for pinpointing (and also is usable with my Titanium knee).
I occasionally put a bigger coil on, but must be very careful to keep it well away from my knee