Is it possible to modify the mod in a way that the mining productivity tech would affect the deep mines?

Mining efficiency only affects mining drill and pumpjack entity types.
Changing the type of deep mine to drill would require generating infinite ore beneath each placed deep mine.
The entity size would start limiting the number of different ores. a 3x3 mine could only produce 9 different ores, which might not be enough when using angels.

If you were to make it a 4x4 entity, could it then do 16 different ores? And then a 5x5 25 ores? I would think at least one of those should be able to handle the amount of ores, right?

At the very least, it should be possible to have different tiers of these deep mines, which could mine more ore faster, built from a deep mine and some other bits like iron and steel, and maybe even dynamically requiring bits from bobs and angels?

Or maybe it's fine as it is now, I should probably try the mod first :D

The devs may be persuaded to add productivity properties to assembler types.
I'm waiting for a positive or negative reply on that before hacking together a miner workaround.

Update: with 0.17 Deep Mines are affected by mining productivity.