Some people have apparently had problems with the deck bouncing. The decks already rip up the turf enough with the anti scalp wheels because the decks are so heavy, so adding springs for down pressure wouldn't be the best idea, IMO. If anything, add swivel anti scalp wheels, springs to hold the deck up a little, a solid lift system (not chain; look at kubota's), and shock absorbers to prevent bouncing.
With the mid shaft pto, optional front mount flail brush mowers, sweepers, snowblowers, etc could be easily added. I like the all integrated kubota transmission; there is no belts connecting the hydros and pto, and no hoses between the pumps and motors.
spelled with a g!!!!!