I tried the L size of ortfon tips( hate this crappy name) today. It stays in my ears just like S and M tips although I get a little discomfort when yawning xD
I didn't feel any sound signature difference between them but soundstage. I get better separation when using L tips but less detail comparing to other tips, and with S/M tips I hear more micro-details in the background but more centric sounding.
Also I have noticed that sibilant problem on 1+2 is not bothering me anymore..It has more controlling on that area :D