I have the Double K Challengair vacuum, and love it! I got mine from Jeffers Equine.
I have an allergy to horse hair/dust so spring grooming is not good for me. With the vacuum I can get all the loose hair off the horses without getting it all over me & without having a major allergy attack, so this is all good.
Lots of pros, no cons that I can think of associated with my vacuum!
But not all is lost, how I found the great deal - I went to Metro Vacuum's website and looked at every single dealer and compared prices. I got a steal on mine, I saved $60.00.
I like it, it is heavy duty, 4 HP. I can hang it and the hose is 15 ft long, so I can go anywhere in a stall with it.
We have two shop vacs that we use on our jobs but I stole one to use in the barn. One is from Home Depot and the other one is from Harbor Freight. It is very loud to the point that it is annoying but it does ok and the horses don't seem to mind the noise and they both have good suck. However I've come to the conclusion that I could do just as good if not better with a brush in each hand.
We also use a shop vac. The small one. Nata found a special attachment for me that fits the hose, and is for horses. I don't know where she found the attachment, but it was only 19.99. The shop vac is inexpensive, can be used wet or dry, and lasts a long time.