Experimental Units,More Freedom of Choice for units etc

Came up with a idea right now,with certain tech trees,you could choose between a few units,every unit has a flaw,but that's part of realism,so say for the german tech tree,with the tiger you could choose between the henschel tiger and porshe tiger,although the porshe tiger will be significantly slower and cost more resources,but will be tougher with a frontal plate of 200mm instead of the 120mm on henschel,of course ridiculous,but also maybe for the soviet tree with aerial units you could chose between the Yak-1 or the I-225,of course the I-225 would need more time to be built as such and cost a few more resources,then with soviet heavy tanks,with the first level you could choose between the KV-1,T-100 and SMK,and for medium tank level 2-3 you could choose between the A-32/A-20 or the T-22 (TG-1 Grotte for the ones who don't know),of course this is a ridiculous idea,but the thought of playing with it is interesting,please feel free to add any ideas as such

And no i'm not saying add the maus or E-100,but meh,each to their own

I was talking about research btw,i just realised i didn't say that,i just said tech tree

please provide feedback if possible