The 540 is great, we have almost 2000 hours on it, but it only sees action on the really big trees or projects where it is useful to use both machines at once. The giant really fills the void for most jobs. It is lower impact, so we don't have to worry about using plywood as often. We have the aggressive dual tires for rough terrain and the turf tires for the low impact lawn work. The lift height on the giant with the telescoping boom is darn near the same as the the bigger 540. The giant also fits perfectly on the same trailer as our Carlton 7015, where as we need to bring a separate truck and trailer for the gehl. Not a huge deal, but it is more efficient for us.
Our vermeer mini is 10 years old and never sees action any more. And as much as I loved that machine, if I were to start all over again and buy my first machine to forward material, it would be the Giant. It blows the doors of the mini, it's not even close. Faster ground speed, higher lifting capacity, higher lifting height, more turf friendly, and can still fit through a 36" gate. It is the real deal.