Yes, they fit.
No, no mods are needed.
Sound quality is unchanged.
Losing any of the official proprietary tips would be costly to replace. Complies are much cheaper.
Regarding comfort, this is likely to vary from listener to listener.
The seal is better for me, providing slightly better isolation, but most importantly, they no longer fall out of my ears so easily.
Sorry but that's just ridiculous. Comply's only need to be replaced when they start breaking down which depends entirely on how much they are used. Bacteria and germs can live just as long on silcon and other materials as they can on foam
Do you disinfect your silicon tips weekly? Maybe your ears are just dirtier. If you clean your ears regularly and properly, you are not going to have dirty tips are you? In any case, there is nowhere that it is recommended to replace Comply's weekly.
Mine have failed at the juncture of the iem to 2.5mm plug cable fitting. First one ear went out (w/no warning or intermittent signal period of deteriorating sound). A few days later the second went out as well. I've tested the 3.5 to 2.5mm Sennheiser supplied cable and it's ok. So it's definitely the cable to 2.5mm plug connection where it looks frayed and loose. Has any one else had this issue? Did a search on Head-Fi and could not find related. Sorry, did not read all 130pages of this blog.