RNAse Protection Assay for microRNA - is anyone using the mirVana Detection Kit? (Nov/10/2006 )

Hello,
I'm interested in tracking the expression of a specific microRNA in S2 cells. I want to avoid the Northern so I'm looking into painless alternatives. Does anyone have experience with using the Ambion RNase Protection Assay to detect microRNA? What are possible problems? Why is this technique, which seems easier and more sensitive than a Northern, not used more often?
Is there something else I should try? (Anything cheaper?)

Thanks in advance for any input.

It is not very convenient, there are many steps that you need handling of radioisotopic than classic northern hybridization blot