I've had two 6290 dyna 4 and 2 6480 dyna6.
Everyone blows about the dyna 4 and defo bit more responsive system over dyna 6. But overall if got a good 6480 05-06 dyna 6 with suspension and perkins engine I'd not pass. Had 2 and drove stones of them from balers mowers dumtrailer lowloader and hardest bit on them drawing and stacking bales.
1. Field work mowing could not fault in any way best gearbox I've used.
2. Drawing and stacking unreal tight turning will work in tightest of spots and still good size tractor so no need to weight back steady as rock with bale on loader.
3. Dump trailer low loader my only fault with them is the delay in gears for road work. Only dyna 6 ever had was 6495 that doesn't have delay and it's an animal to tow.
4. Reliability near no problems at all gearbox touch wood is bulletproof never changed a clutch yet and have 4 dyna 6.
5. Perkins engine well in my experience sisu is the no 1 but I've had many perkins and 10k on 6290 and never had spanner to it and it still put it up to the bigger masseys in the yard
Get a mid hours 05-06 massey6480 defo front suspension fool to get one without. And you wont get a better all round tractor contractor or farmer.