If a Sith uses transfer essence on a person with a lesser aptitude to the Force (ex: 2500 midi-chlorian count) will they have the same connection to the Force as their original body?
I am aware midi-chlorian count isn't everything to be adept at the Force but it is still is a good factor.
Apparently yes, Sith Lords carefully selected their targets.
Transfer Essence is a skill from Legends. As such, there are even less rules than in Canon. Yet, some things could be concluded. There are cases where Dark Side users transferred their essence into objects (buildings, talismans, etc...). In those cases, their powers were severely restricted and they essentially required another Force sensitive being(s) to act. For true transfer of essence another living being was used, but not just anyone.
Darth Bane, in his failed attempt of Transfer Essence targeted his apprentice Darth Zannah. She managed to resist, but the fact that Bane risked so much (instead of selecting first nearby being with weaker mind) testifies that he wanted someone with high Force potential in order to preserve his powers.
Palpatine and Set Harth used their own clones for ritual. This was pragmatic solutions, since clones already had same genetic code (and possibly same midi-chlorian count) as original body, allowing for smother transition of spirit and retaining of power.
Finally, Vitiate, as possibly most powerful Sith ever (in Legends at least), although able to survive even without body, still preferred to inhabit Force sensitive individuals. For example, one of his Voices was Voss mistic. Vitiate transferred his spirit into him specifically to be able to use Voss power of seeing future, implying that he could not do this on his own, and that power still remained in the body although spirit of previous inhabitant was crushed by Sith immense power.
All this points to conclusion that connection with the Force and Force power do depend on the body of unfortunate host, and that parasitic Sith could not just simply select anyone and hope that everything would remain the same as before essence transfer.
