I think he means swaping the driving squad of the ambulance with REs.
Perhaps he's asking if it's viable.
Problem is is that if you lose the ambulance you lose a more combat effective than the medics squad, which is also your main builder and repair unit, as well as their ability to volley fire which may be crucial in some early game parts in order to gain ground and force the enemy to retreat.
But yeah, you then have 2 healing units and the REs can repair the ambulance.
I'd say see how it works out for you and then maybe report back here.
Sorry if I was a bit unclear. I was thinking that if you lose an ambulance it would hurt less if you have the medics already out. Then, you will not need to rebuild an ambulance for the heals. Alternatively you can have the medics out on the field healing squads that just got out of combat, also increasing field presence.
If that is indeed the topic (for I am also unsure), my suggestion would be to wait for the next patch to drop. My attempts to do it ended just with frustration from my medics not healing unless I microed them to do it or chasing my units when I didn't want them to - both things which are set to be fixed by the next patch.
Yes, this will help when these bugs/oversights fixed.