I could be wrong, but my impression is that SLC has the largest senior cohort, with Iona's probably larger than MCAs?
The fact that SLC is not involved in a single "A" final other than the First XV must be a bit of a concern for them.
Not sure it is an issue for Lauries just yet. You have remember they are trying to recover from a decade of poor engagement (even finishing 5th in the aggregate one year) which was unheard of). That trend is slowly being addressed but takes time.
The challenge for Lauries is cultural. MCA has exceptional coaches, especially at the junior level and Iona too has a very good program with a lot of boys taking advantage of the C2K Academy.