I have been playing my P790s for over a year now and could not be happier with them. When I was fitted (it was my first fitting ever) they suggested a 2 degree up lie. I was use to play a off the shelf with a standard lie. It took some getting use to the difference but it does make a difference having clubs that are fitted properly for me. I would give them a little more to for you to adjust to the differences, just my opinion though. Although, if they were suggesting a 1 degree up during your demo I am suprised they did not have you hitting a club with that setup.
I experienced a similar situation with my P790s. I was custom fitted by a Taylormade rep, which setup my clubs 1* flat the rest standard. I received my set and could not hit them. Turns out they were not setup to the correct specs. Some of the clubs were 1* upright and others were standard lie and not 1* flat. Also, the lofts were off. I returned them and they ordered another set. SAME THING! Returned the set again and order another set. I was told by the golf store that they have seen the quality of the TM clubs go down. After receiving my third set, I went to Cool Clubs to spec them out. Had to make a few adjustments and love the clubs.
You may want to have your clubs checked out by a reputable golf fitter. Cool Clubs uses very good technology to measure your clubs loft and lie. They even have a device that measures the stiffness of your shafts.