Well you can buy Powerpoints up to your magic attribute during character creation. The problem is raising your Magic attribute to 6 if you did not start with Priority A Magic.
And if you do select Magic A, then you end up with a really average character beasaue you either miss out on skills or attributes... you cant have everything with the priority system.
I personnaly tried to build a Face Mystic Adept who can atleast handle himself in fights and... I cant do it. He ends up with a lack of attributes or skills.
No it ends up being totally broken unless you build your character to suck. Just build a mage, now add 6 PP instead of astral projection, you just are better than the mage hands down and as you advance you will just get better and better than the mage. Just pick powers tha are skill neutral like combat sense, or mystic armor etc, or for the skills you had points for. You basically tried to cover 3 sets of things, magic, face, and bad ass sure you will fail. Anyone who doesn't go crazy will be flat out better than the mage, and mages weren't exactly the weak archetype in the game. At 5 per PP it is still broken due to how you advance getting both PP and magical juju. In SR4 we had plenty of mystic adepts and they were actually balanced with the rest of the team.
I would have preferred totally splitting the magic attributes. Mystic Adept A would get you 6 in magic to split between Mage magic attribute and Physical adept magic attribute, 2 totally seperate stats. It would be similar at launch to 4e, but due to it being 2 smaller stats and stats increasing in cost at attribute shooting for x5, they could advance the attributes quicker.(going from 6 to 7 is 35 karma for 1 pooint in either adept or magic, but if you have a 3 and a 3, you could increase both to 4 for 40 karma) and with starting karma you could go 6 magic for spell casting 0 magic for physical adept, use karma to raise physical adept magic to 1,2,3 for 30 karma or the reverse.
Whether you are a mage or Mystake adept you are going to bump into the same skill/attribute problems. Lets say A skill B magic, C attribute. Sorry but 16 in attributes just suck, you are going to be mostly 2s, with a 3 and your drain stats are fine. It doesn't matter if you are a mage or an mystake adept your attributes suck. It is not hard to either focus on things not related to any attribute/skill or to the ones you happen to be good at.
Want to make a mystake adept, build a mage and just make him a mystake instead you just successfully upped your power.