The rubber hood sounds nice in theory, but doesn't work in practice. There are cutouts in the factory hood for a reason. Your photos will noticeably vignette at wider angles with a solid ring-type hood without cutouts due to corner shading.
It's a pretty trivial matter to flip the hood around in the bayonet mount for backpack storage - I've never the slightest problem in 12 years.
I bought a used hood to replace a lost hood at KEH a couple of years ago. The earlier poster talking about wear on the lens bayonet is correct - the hood gets noticeably sloppy over time. I usually slip a tiny piece (thumbnail-sized) of kleenix tissue in the groove when I am putting on the hood, which tightens it up perfectly
Leigh
zippski