You only have Magic 2? Yeah, that's going to be a pain... But then, a mage with Magic 2 is supposed to be ineffective.
If you could rebalance it so you have, say, Magic 4, you'll have a limit of 8, which is plenty. The power focus will still help you a lot. Drain being Physical is a pain, of course, but some of your cyber is probably spend mitigating that, and there's Fetishes and Centering; the drain value is the same, after all.
Hm. Kincaid, you might just be a genius. He could cast that Force 10 Fireball when he really has to...and then just pray he's up to the task of soaking physical drain for pretty much most of his spells.
Actually,
that you can't do. Reagents set the dice pool limit, not the Force. Your Force is still limited to 2xMagic; you could at most cast the Fireball at F4 if you have Magic 2.
What the reagents allow you to do is to then ignore the Force
as a limit on the dice pool. So if you roll 8 successes, you can keep them all, instead of the 4 you'd normally be limited by. It still counts as Force 4 for all other effects, though; Fireball specifically is bad for this since it uses Force as base damage.
The reagent trick works well with a lot of spells; Increased Initiative, most Illusion spells, mental manipulation, direct combat... everything that uses Net Hits as it's main basis for the effect. It doesn't work well for Indirect Combat, Mental Damage, or other spells that mainly use Force.
Still, reagents work well as part of the solution; you just have to be careful about which spells to pick. Plus, Force, not successes, is what determines drain; if you cast all your spells at a low Force and then use reagents to increase it, it matters less that your drain is Physical (since you're likely to ignore all of it).