Yeah that sounds wise. I was a little worried by the overheads, but figured it would be okay for this. For my mod I could need to pull quite a few avatars so I will give your suggestion a go.
P.S. I was trying to look up the function in the SMF functions database but for some reason it's been down since yesterday it looks like. They're working on it. What I may do is take a look at the details and maybe post an alternative.