Using a blender to mash potatoes releases the starches in them, which turn it to glue. Best always to simply mash it, either with a masher, or a fork. I've successfully frozen mashed potato (no butter or milk in the mix), and it has reheated without problems. And I generally use the standard brushed/coliban type that are usually the cheapest anyway. Using a blender is fine for all other vegies. I make potato only cubes, and then a mixed vegie cube (pumpkin/sweet potato/corn/peas/brocolli/cauliflower/carrot etc), then reheat & mix it all up just as I'm serving it.

The other thing you can do is to microwave potatoes in their jackets for a few minutes (my microwave takes between 5-7 minutes to get to the desired softness, depending on the size of the spud obviously). The red skinned ones like pontiacs work a treat,as do desiree, they go really "fluffy" and just do these as you're preparing their dinners. Not quite the convenience of taking a cube from the freezer, but not that much more effort. I just scoop the flesh out, and do a little fork mash. If I can be bothered, then I also finely chop the skin up, so that he gets the goodness from this too, but that's not often....

but - never use a machine on your tatties, unless you want the glue..