Every time I've done a search the cyclomethicones are described as volatile carriers, in other words they evaporate after aiding the delivery of other ingredients so I don't see how they can build up. Dimethiconol is another matter.
However, one thing that can end the total 'cone-phobia is knowing that fruit/seed/nut oils, especially combined with essential oils such as peppermint, eucalyptus, lemon, lavender and thyme can actually dissolve silicone polymers and plastic resins used in conditioners and styling products. A few years ago I helped circulate an Aveda article about this because they had a salon product for this very purpose. The article, which unfortunately doesn't seem to be available anymore, explained very well how/why this worked and it helped many CGers better choose their wash CO. Personally, I'd been lucky enough to have started out with a CO which contained tea tree and peppermint oils besides 2-3 seed/nut oils so I never had any problem with build up, even when sometimes I had to use a CO or styling product with 'cones. But happiness doesn't last and the formula was changed so now I guess I'll have to add the oils myself.
Also, some say vinegar rinse doesn't remove 'cones but during a search long ago I found that ascetic acid does break down pretty much what the above mentioned oils do. I survived 45 days of using a cream gel with dimethicone every 2 days at a time I didn't have my usual wash CO with me. I had started doing white vinegar rinses to get rid of scalp build-up and continued using it because it also kept my hair build-up free. However, if the water is hard, vinegar will NOT be enough to combat both.
As for Frizz Ease, if I remember correctly it contains several other hard-core 'cones as do most anti-frizz serums, so I doubt cyclomethicone is the villain there. However, I myself cringe at the thought of using that at all, perhaps once in a very blue moon for straightening purposes only (followed maybe by a shampoo and DT) but certainly not as a general routine for curly hair, all those 'cones WILL build up and eventually suffocate the hair by keeping moisture out.
2A/3A, medium length, layered, colored dark/medium ash blonde - "CGer" since April '02.
"Converting the 'curlskeptics' one curly head at a time..." HWHC