I certainly wouldn't install a power top just because the rain can creep up on you. And it doesn't really creep up on me or suprise me where I live; it was a sunny day when I drove it to work, and clouding over when I drove it home at the end of the day. Half way home, when a few drops appeared on the windshield, it was time to put the top up.
I don't know how long it takes the top to go up and down... never timed it, and the battery is unhooked at the moment... remind me to clock it in May! I would guess it takes somewhere around 15 seconds? That's a real rough guess.
I hold to my other point though; my car is almost as old as I am, and to have an (almost) 40 year old car with a power top that functions great.... well, for me it just adds to how special these beasts are. Not to mention the "whine" sound that it makes! I'm guessing the new Solstice doesn't make quite the same noise!
Having said all that, when my system self-destructs one day, it'll probably be a manual top from that day forward! In the meantime, I love it. (Have I mentioned I love the power top?)
PonchoMan: perhaps therein lies your answer: if you haven't experienced a FGF power top before, check it out. If you think it's really really cool, as I do, maybe you go for it one day and spend the $$$. But if your reaction is "Eh, no big deal.", then you wisely invest your money elsewhere.