My DD1 is an Eloise. We know a couple of others and do hear the name out and about but are aware of the name, because it stands out iyswim.
In her primary school of 200 children, she is the only one. In her previous school (before we moved) of 270 infant children, she was the only child with her name.
I tracked the statistics when she was born (so from 1998 - 2003) and then again when my DD2 was born (2001 - 2006), and in that time the name hit the top 100 for a few years, got as high as the high 70s (maybe 78 or something like that) and then fell again. It reached its peak around 2003-4, I seem to remember. It stayed around the top 90s for a few years, and then fell out of the top 100.
Given the fact, that it never got as high as the top 75, I wouldn't say it was too popular. The only thing it is similar to is Ellie and Ella. There are lots of those around my DDs age (10), but I only actually know one little Elise and no little Elodies, so I don't know if they're that popular. Certainly, There are not that many Ellies or Ellas these days.