I agree. It's very amusing, and is great as a colloquial pet name, but I can imagine the authorities resisting it. "Evidence of the regrettable interest in archaeology by the great unwashed..."
I'd originally thought Little Silbury was a bit demeaning, but maybe not. IF it's ancient and IF it seems to be of similar form and function then the name Silbury has got to be in there. No visit to Avebury would be complete without looking at them both, as a pair.
Incidentally, if it is Silburylike, doesn't that create a new monument type, Spring Mounds? Silbury spring mound and Little Silbury spring mound...
Oh dear, I hope it's not medieval.