I got one that is the lighter duty of the two, my kids borught it form me for xmas , I have had no problems from it, would of liked the HD one, but find the one that I got great, and pumps the tyres up no problem, just a bit slower. but quite quick still.
If you can spend the money then get the HD, but the LD one is good as well.
i have a britpart twin pump, is the silver one, same as all the other, different brands etc. apparently 150ltr/min free flowing.
anyway it takes about 6-7 minutes per tyre to inflate my 33x12.5x15s from 12 psi to 35 psi.
i would always recommend the largest pump you can afford - waiting around for your tyres to blow up whilst your mates are already heading home is no fun.