Air volume and sustained pressure is king when blasting.

I have a 5 or 6 HP with a 60 gallon (I'm pretty sure) tank Black Max and I only generate about 100 psi or so that I use in the way you are talking about not sure about your 5 lb 150 psi statement. I have had the $250 Harbour Frieght cabunet and a 80 lb gravity feed canister blaster. It will keep up with the cabinet fine but runs constantly when I am working, it works with the canister but will literally run it out of air in about 5 minutes which causes it to use more sand. It works like a b!tch out of the gate but when the pressure drops to 60-70 it is less effective, still works just a notable differents, when I recognize it I stop and let the compressor pump up. 5 minutes may seem like a long time but it really isn't when you are blasting larger objects with less than optimal pressure. I could increase it's time span by added another storage tank but really haven't needed/choosen to do it. It definitely isn't good for the compressor.

If/when I have to buy a new compressor I would go with no less than an 80 gallon tank but really as big of a tank as I could afford at the time, even consider refurbushing an old gas station compressor ( I actually have an old dealership compressor I need to redo).

Hope this helps.