I haven't seen any research but my common sense says that if you wear them all of the time and they want to get down and roll around etc. then you will be delaying their potential development.
If you leave them down despite the fact that they want to be carried by you all of the time then they will hate being left and down on the ground so again you will be delaying their development.

Also remember that development is not just physical. Brain development is huge in the first year and is very much parent guided. If you force them into separation from you so they can be on the ground when they really really don't want to be then again their are likely to be negative impacts.

So I think you need to be guided by them. If they need to be carried around a lot then do it. If they want to get down then let them. They will then have confidence that you can provide the emotional support that they need, and develop the physical milestones in their own time.

I HTH.