I don't know how much power it takes but I can assure you it takes power and that its a parasitic loss I can live without.  Assuming your tractor has a hyd pump why not use that one? 

As for the hoses, it only takes about 2 seconds/hyd hose to hook them up and I've got hyd lift and swing so I've got hoses anyway. 

For us hooking/unhooking isn't much of an issue because the grinder hardly ever gets unhooked, basically the only time that tractor gets unhooked is if it needs to be worked on.