I think they fail to sound as open and transparent as the meelec balanced. They have some more harshness as well but the bass is powerful, the mids are clearer and they fit like a glove. But again, I love my meelec balanced with a pair of soundtubes from comply tips to make the fit easier and seal better in my ears.
Edit: Also. This is from memory. The reasons I remember not wanting to use them. I revisited the ones I did like a month ago or so and still found them to sound quite similar to my memories of them.
To my ears these are good matches:
Meelec balanced - open, transparent, less mid bassy
Sensorcom biflanges - deep bass and quite a lot of mid bass, quite transparent, good treble, not as open.
MH1C hybrids - strong bass response, good balance in mids, a bit aggressive less open and more directed but still good placement.
Comply TS500 - Softer sound, comply-ish bass texture, bass lines really stand out. Upper mids are softer and more relaxed. Treble is a bit more subdued.
Not as good:
Auvio tips - a bit harsh, strooong bass response, sound veiled in the upper mids and lower mids take over. A bit sibilant treble.
Comply T500 - sound like a more claustrophobic version of TS500 I prefer TS500 over T500.
UE900 single flanges - quite similar to auvio tips.
Generic stock single flanges - bassy, veiled upper mids. A v-shaped signature that's also quite fatigue free but I think there are better options.