I rather like that, it's a nice twist.
I haven't tried T5 (yet) , I'm still an MT kind of guy with a weakness for FF&S.
I've liked the idea of stealing some of the modifier rules from BTRC's
"Vehicle Design System" and "Guns,Guns,Guns" on these topics and using
them along side the MT rules. ... but those are design-time modifiers,
and lead to a lot more spreadsheet action than what you've got here.
Your idea is a bit more abstract, but much cleaner and more straightforward.