I got my RE license as a means of targeted learning about RE, but being that it was a side endeavor and my main job salary and satisfaction kept improving I never made a full jump into RE agent-hood and hanging my license with a broker.My question as a potential primary residence buyer in new big-builder home purchase, could I hang my license with either a 100% commission brokerage or a broker friend for the transaction to retain the buyer's commission?

To directly answer your question - I don't think it will impact a renter but another buyer may have the same thoughts you're having now. 

If a house goes from $100K to $110K, I see the cash buyer making $10K, but over all the loan buyer would still loose money in the long run.

@Aaron Hunt, as I shop around I am finding that when you go over 80% CLTV lenders are requiring an appraisal.

Seller must provide an up-to-date lease agreement of every tenant (no month to month or handshake agreement)Seller must provide last 12 months of rent rolls (showing that every tenant is paying on time/no deadbeat tenant)If there is a security deposit, it needs to be signed over to the buyer at closing (so that the renter isn't required to pay another security deposit to start a lease with you)Is there a Property Management in place?

While they may not be super interesting to most retail buyers, they make for good rental properties oftentimes.  

After doing research and educating myself on this method, I found the sellers are the hardest ones to find, not so much the buyers.

A house is only worth what a buyer is willing to pay for it .  

The new buyers were either shifting lots cash from some place else and were not worried about returns vs. asking price,   or are expecting to get around $2K per unit in a seattle suburb.  

I'm assuming the house is furnished being a model home and that the builder is "renting" it for purposes of showing the house to prospective buyers in that development.If the above is correct it's possible the buyers could insure the house as a vacant property.I think an attorney should write up something for both parties to sign showing the builder assumes liability while showing the home.