By "Ultraplus", as a vendor, do you mean Ultrapower?

If so, you may as well go that way as they are the importer/brand owner.  That will remove one layer of hassle, the retailer, when the trouble starts.

Good luck!

Oops, yes, Ultrapower.

"When" the trouble starts..? I thought these were reliable boxes?

I had a very, very, VERY bad experience with an Ultraplus 980 HD (more accurately, 4 of them), and a certain retailer (on your list, by the way, but not Ultrapower).  I'll not be passing that way again, but with a different model, and a direct channel to the importer, maybe you'll be fine.  That's where the "Good luck" part comes in.