skibug, E-series is an option. The advantage is that it is lighter over the standard FM system, (they claim the lightest, I don't know about that) but it does not offer the simultaneous release that the standard system offers. Each boot releases separately (the cuff releases in fact) much like a rubber boot.
I use the standard FMs for years now without any problems, however one must be extra careful installing them properly, otherwise pre-release issues may occur.
The weight of the standard FMs is an issue, but not a big one imo.
I believe the first question anyone has to ask is if you want a simultaneous release or if it is not that big deal for you, then you select the system that best caters for your needs. If I was not worried about that then I would probably go for skitech - rubber combo, because it is important to me I opted for FMs QD6, other options in this category are Goode powershells (have pre-release issues, but are very light and responsive) and the Fogmans (I have seen them failing many times so I stay away, never tried them myself)