I've been using using comply tips on all of my IEMs for years now,
started with medium T-100s which I actually still have 1 pair left, they are small, minimal size really, 10mm length 12mm diameter,
the best ones I've had were T-100 large from early 2013, 14mm length, 13mm diameter, no guard on them,
but when I re-ordered those I found that they had changed the design to a shorter wider version, closer in length to the original mediums, these measure roughly 14mm diameter and as such they seem to exert slightly too much pressure on my ears and lack the depth to get good isolation.
So I switched to the P-series which are much longer, 15mm + length, 13mm diameter, they also have a tapered core unlike the T-100s, so they feel slightly different when rolled and possibly isolate better.
The issue I found with these though is that they are actually TOO long, this might be great for use in very high noise environments, but for general usage I found that the hole would actually close up and muffle the sound because the insertion was too deep, so I had to actually cut the end off to hear the sound clearly, its difficult to get a straight cut since they are foam and you lose the nice rounded shape that complys have. After that you might notice an additional problem, the long core inside resonates strongly at certain frequencies ( around 4 to 8 KHz ) like a reed in a wind instrument, adding a slight harsh sound to the music, to fix this I had to force back the remaining foam past the end of the core and cut around 2-3mm off, not easy.
I give it a high rating anyway because from what I've seen theres nothing else you can buy that will produce the good results you can get with this.