I have never borrowed from a HML, although I will later on this year.
I, too, would love to borrow as much as possible, BUT I try to put myself in the HML's shoes...
If I am a HML and someone with very limited or no flipping experience asks for 100% funding, I would not do it even if it were a smoking hot deal. My reason being...I, as a lender, do not know you (the general population you) and what your strengths/weaknesses are. Even you bring in a top-notch professional looking request with solid numbers and glossy pictures, along with a business plan, I don't know how you will execute to those numbers and the plan. I know that you will say you have great people & project management skills as well as follow-through and will manage to budget, but I do not know that for sure until I SEE it and experience it with you. Because of that, I would not be willing to lend 100% and have all the risk on me, as the lender.
Once I get to know you with a few more deals done, then rates and numbers can work more in your favor.
Just putting myself in the HML's shoes like above...I expect to approach them with 25-30% of my own money available to put into the deal. No matter what I say, they won't know me from the hole in the wall. So in order to use their money, I feel I would have to step up with some of mine, as well.