JAD: I see your intent but it needlessly changes a system which isn't all that broken. There are far too many things in the system which key off Magic in awakened and magical entities. It's the one quality which they all have and you remove that. (Enchanting, wards, assensing, magic linked adept powers, background counts, magic loss etc. big list).
My recommendation to others is to allow Adepts (not mystic adepts though) to use the optional rule to gain PP instead of metamagics while initiating. They can also use 15karma here and there to pickup the oddball metamagic they wish to know now and then (adept centering, masking, and the like...). I've found this works extremely well given the extremely low cost of initiating compared to magic... while still forcing them to raise magic occasionally.
Reasons:
I've played in a game where adepts were permitted to buy metamagics for raw 15pp... then combine it with the other optional rule to buy power points instead of initiating WHEN INITiATING. My reason for emphasis is that the optional rule clearly states WHEN INITITiATING an adept (but not necessarily mystic adept) may obtain a PP instead of a metamagic. The other rule deals only with learning metamagics and has nothing to do with PP's. And this was all written long before the SR4a karma cost changes to attributes and karma awards (remember karma costs went up, but book karma awards were also increased).
It was a disaster. There were FAR FAR too many power points floating around. Especially since Attribute at 5x cost couldn't hold a candle to free PP with initiation at the much lower initiation costs (remember initiating used to always be much more expensive than raising magic... attribute costs changed that). The 15 karma was written for the old costs and didn't reflect changes in buying PP. All the adepts ended up running round with maximum initiations, and maximum known 'metamagics' and low magic scores. It did not work well AT ALL.
Remember the rules allowed for Maximum Initiations == Magic, Maximum magic == initiations + essence, Maximum known metamagics (PP's) of magic + initiations! So Mag5, initiate 5, was packing 15PP easily.