Be that as it may, the original author is broken.
Allowing the equivalent of 15th level spells in 8th level slots is broken. Even the more potent Sudden Metamagic feats are fairly broken, but at least one can only use a Sudden Metamagic feat for one specific metamagic effect and it can only be used once per day.
As an example:
Arcane Thesis (-1 per metamagic feat added version) Maximize Empower Cone of Cold = Level 8
Maximize Sudden Empower Cone of Cold = Level 8
Both are level 8 and do the same effect, but the first effect can be done over and over again whereas the second is once per day. Plus, Arcane Thesis can be applied to many different metamagic effects. The only difference here is that the first one requires 3 feats to the second one's 2 feats, but the balance here can be seen by taking the Sudden Empowered feat twice (i.e. twice per day for 3 feats versus many times per day for 3 feats, and yes I know, most people take Sudden Maximize as opposed to Sudden Empower, but this is just an example).
WotC balanced out Metamagic Rods and Sudden Metamagic feats by limiting the number of times per day they can be used.
Arcane Thesis with the original author's intent is not limited, hence, by definition it is broken.