The meta speed edge has a lower profile than all of the other carbon fiber racers out there, is it the happy medium for track workouts? My thinking is they’re a cross between an LT stream and next%, which may be better for fast track workouts. Or is a regular flat still better on my quest for sub-4.
If you are looking for a shoe specifically for track workouts then that would be a great option as it's got a heel stack height of 34mm.
I have a pair of Endorphin speeds that I love as they do a great job of protecting my legs for the following days, but their heel stack height of 39mm feels unstable on track turns, so I totally understand why you're looking for something lower stack.
The Skechers Speed Elite Hyper is only 28mm in the heel, but doesn't have the same bounce as the Asics, partially because of the plate only being carbon-fiber infused.
The Streak LT 4 or 7 would be great (the 7 is an old model that has extra heel cushioning, but the same under the forefoot), but would allow your legs to get beat up more than the super shoes. The Streak LT 4 also comes in a spike version and there's the super spikes if you're interested in those (and could find them in your size).
It really gets down to how you would like your legs to feel after workout days.
And good luck on sub-4!