Hobart HSM20 or HSM30

I don't know which one to buy... we would only be using it immediately for short crust pastry and bread loafs... 

I was wondering whether anyone with experience of either or both machine could tell me what the minimum dough or pastry is for the 30 Quart and what the maximum is for the 20. I don't want to purchase the 20 and regret is as it is too small for my needs and vice versa for the 30.... I have read the spec sheets and seen what hobart think the max is but I get the impression that their figure is not entirely accurate. 

Please help ! Thank you so much !