Hi Candyoscar 
First of all, to clear up the 'risk' question, it doesn't matter if you ask for reconsideration or appeal, because either way they look at the claim afresh. So, whether you ask for reconsideration or appeal, they could decide that the original DM was erroneous in awarding HRC, and reduce to MRC or LRC. The risk of being downgraded is something that you need to balance between accepting the award, or pushing for HRM, not between reconsideration and appeal.
As an example, my DD was receiving HRC, no mobility, and her award ran out in the December. I had submitted renewal, as per DWP advice, early. In the August, she was awarded HRC, HRM from December. I phoned and was told that it was because I submitted renewal, and not supercession request. If I had asked for reconsideration/appealed, I ran the risk of losing a 3 year HRM award, for the sake of possibly gaining 18 weeks HRM. I decided that it wasn't worth the risk.
Streakybacon is right, that reconsideration is an automatic first step to appeal. You can request an appeal, but as part of processing the appeal pack, another DM will 'look again' anyway.
I think with HRM for a nearly 5 year old, you have to consider whether her case is 'clear cut' enough. There is no LRM for an under 5, so if you feel she is borderline, or probably meets the criteria for LRM more than HRM, you would be better waiting until she is 5 and asking for a supercession. However, do be aware that in doing that, they also look at the HRC award to check it is still valid. There is no escaping it!