The medic change will have anything near noticable impact almost exclusively in blob warfeare where you mass retreat constantly.
Soviets will benefit from the change barely more then any other faction...
Yes I agree with this. I also don't think that the change will have a huge impact. Yes, Soviet squads usually retreat with more men than Axis squads, but in the end that additional guy now gets healed probably only a couple of seconds quicker.
It keeps selected squad on field longer.
It does not keep your actual map presence topped of.
Its similar in micro scale(you want X squad to have all models back on field) and completely different in macro scale(you want all of your infantry to have max number of models on field without retreating them).
That's fundamental difference.
Of course it keeps map presence up, because you can keep the most valuable units on the field. An FRP does not allow you to keep your high value unit on the field all the time, it just minimizes downtime for all units. Merge allows shifting of downtime from an important to an unimportant unit. But it is usually better to keep your vet3 ATG/stolen MG42 on the field than the vet0 Conscript that would lose the next fight anyway.
The exact mechanic is different, but the function (read the result) is the same.