What size tractor do you use for square bale accumulator?

I am using a JD5525 for a 10 bale accumulator on the front end loader. I was considering a smaller tractor with HST transmission and the JD salesman said the Front End Loader on their 4000 series would not take the stress. Per load capacity should be fine for the accumulator and hay should be about about 70% of it's capacity, I do realize the load extends out a good ways. Tested little lighter accumulator for same number of bales loaded on a NH tractor of similar size as the JD 4000 series and it performed very well. 

 

So make me wonder what size of tractor others are using successful. 

What size tractor do you use for square bale accumulator?