When using glider tips my ER4S sound completely different than their intended 100% deep insertion / sealed sound with triple flange or Etyomotic foam. They provide a rather bright presentation, with surprisingly nice amount of air and lot of crisp detail, especially micro detail, the note weight is much lighter. Also offers the best soundstage width. I use ER4S this way with Matrix M-Stage desktop amp, its also this pairing which provides high coherency levels and separation.
I can't say this is exactly how the ER4S should sound for most though I really enjoy them this way and would go as far to say using this combination of tips, amp would be close as possible turning ER4S into a full-size headphone presentation. (within the possible boundaries of reason). Its quite unique and excellent for hearing ER4S in another light, especially the micro details.
And the comfort far surpasses any other Etymotic tip option,.
Glider tips are intended to be inserted as deep as the triple flanges or foamies and will sound very similar. I think you'd get the same effect with the orther tips incorrectly inserted. The same goes for custom sleeves, where the tip cannot be inserted deep enough.
Really? Do the gliders go in that far? I've never tried to force them, but that sounds impossible with my ears. lol and I wear triple flange deeper than most.