You will have to weigh up the risk involved, as when you request an MR they will look at all/the whole of your current PIP Awards from scratch so there is the possibility of losing your current award of having it/them reduced.
You have one month from the date of the PIP Decision Notice letter to make a written request for an MR.
As you may know, Enhanced PIP Mobility "Moving Around" is considerably harder to qualify for than a DLA HR Mobility Award.
The main reason being that the benchmark "walking" distance has been dropped from 50 metered to 20 metres, and you can no longer gain an award for being "Virtually Unable to Walk" as you could with DLA.