What about modifiers just to life recovery rate, rather than modifiers to "leech recovery rate"? Are those applied after the leech rate is determined, before applying to the actual life recovered?
Such that if you also had "50% increased life recovery rate" in your first example, you'd gain 60 life per second for those 7.5 seconds, instead of 40 life per second? And in the second case, instead of gaining 230 life per second in total, you'd gain 345 life per second in total?
So to follow on from the example, let's say you also have 10% of Life Regenerated per second, so 100 life per second from regen.
Total recovery is therefore 330 (230 leech + 100 regen), and that number is increased by generic modifiers to life recovery rate.
This is not ideal (recovery rate modifier gets applied separately to more specific things, and thus ends up multiplicative), but before now there were things that prevented changing that, and now we can't change it without adjusting all the stuff that's balanced around how it currently works, so that's not going to change for a while.
EDIT: fixed typo on the regen number