I've only tried the Flex twice and I'm not a fan. The anal probe/arm is distracting with the texture. It's also isn't girthy enough to really be enjoyable. The actual dildo portion is just too short. It sucks because I had really high hopes for it. I mean I drooled over it for awhile before making the plunge. Boo.
Awhile ago I ordered the O2 Cush because I wanted to try out Tantus' version of dual density silicone; I'd already tried VixSkin and loved it! But to my disappointment, the Cush was really firm, pretty much just like regular silicone.