For what it's worth I think the silicon caps are useless. They are a little longer so could possibly cut leakage along the edges.
But this doesn't seem to be where the leakage occurs.
My eGo T's (A and B) both leak occasionally. After putting on the silicon caps they still leak about the same. Certainly no cure.
By the way, I was vaping 100% PG. Then I read that the T's like about a 65/35% PG/VG ratio. So I added some VG to my juice and it does seem to have cut down on the leaking, especially on the B tank. This makes sense since adding VG makes the liquid thicker, so less likely to leak through small holes.