If your GM lets you do stuff like take PPs as Metamagics and buy an additional Metamagic per Initiate grade, then, hell yeah, go magic ninja all the way. If a PP costs 9-15 karma, it's golden, but, if you're not playing with those optional rules, buy some muscles and get that booster. ~30+ karma for your next PP is no kind of bargain.
Synaptic booster 3 at 240k, it isn't exacty cheap either especially if you need it at alpha or beta grade to not loose a magic point, thats almos half a million or million nuyn for that fourth iP.
As has been pointed out elsewhere, the pure physad is the least Nuyen-hungy build in existence. And, unless you're counting on Power Throw 6 to make your guy the best ninja ever, it might just be worth it to drop two points of magic, knock that Power throw down to 4, and simultaneously free up 2.5PPs and .5 essence; all by getting the SB3 instead of using the IR3 power. That .5 essence can easily fit a R3 Attention Coprocessor and lvl 2 Reaction Enhancers. Or, if you're swimming in cash, R2 delta-grade Muscle replacement is only another 100k. That right there is almost enough to directly compensate for the loss of the two DV from the Power Throw, plus it adds 2 more dice to a lot of very useful skills. Use one of the freed up PPs to take Missile Mastery, and you've got your DV right back up, with 1.5 PP left to spend.
Breaking it down:
Pure m6e6 physad - Power Throw 6 [1.5 PP] + Increased Reflexes III [4 PP] = total 5.5 PP +6DV thrown +3 Rea +3 IP [0.5 PP not spent]
Modified m4e4 physad - Power Throw 4 [1 PP] + Missile Mastery [1 PP] + Synaptic Booster 3 (std) + Muscle Replacement 2 (delta) = total 2.0 PP + 6DV thrown {+ 3 Rea + 3 IP + 2 Agl +2 Str (factored into DV)} <-all of which are immune to BC. [2 PP not spent] cost 340,000¥
Or modified m4e4 physadd - Increased Reflexes 3[4PP] + Muscle Augmentation 4(alpha) + Muscle Toner 4(alpha) + Suprathyroid Gland(std) = Total 4.0 PP {+ 4 Rea + 3 IP + 5 Agl +5 Str +1 Bod} cost 165K¥ <-is doable in chargen
