Shrapnel, having used both I assure you that a bikini cover comes off just as fast as flipping the lever on two scope caps. They protect the lens from weather quite well too.
If scope caps are what you have to have then put them on Leupold scopes as theys are the best ones I have seen.
I have a bikini cover, but figured they were something I would get lost in the excitement of shooting. I am not as seasoned as most on the Campfire, and I could lose the bikini...
In fair weather, just take 'em off when you uncase the gun. In foul weather, just stuff the darn things in your pocket when you're ready to shoot. Seriously... it's not that difficult, and removing them can be just as fast, if not faster, than manipulating the flip ups.
