I make my buying decisions based on what I need/want at the moment and what I have reason to believe will be available in the near future. So far it's worked out for me. A few years ago I was on the verge of buying a Kindle, but the rumor mills, which had been churning for years about the possibility of an Apple tablet, began to take a more serious tone. I postponed my Kindle purchase because I thought the rumored Apple Tablet would suit me better, and a couple of months later the iPad showed up. So, yes, rumors are not facts, but you can use them to make educated decisions. Am I still waiting for my iPhone 5, my iPhone with a 4" screen, my new dock adapter? Yes, for about 2 more weeks.

Rumors on a smaller iPad have definitely gained a lot of traction as well. I won't be surprised at all if one shows up before the end of the year. I will be surprised if we don't have one by next spring, but it could happen. As you point out, not all of the rumors bear fruit. I haven't heard a specific rumor about the retina display iMac, so it hasn't gotten a "ton" of traction in my circles, but there has been speculation based simply on the fact that Apple has started moving its retina displays from it's iOS devices to its OSX devices. I wouldn't call that a rumor, but rather a reasonable extrapolation based on current trends.

But this only marginally ties into the original point of this thread. If you want a computer to take touring, there are lots of options. I like the iPad, but there are certainly other ways to go. As far as I can tell, a change in the dock connector only affects you if you're already a user of Apple products, and if that's the case, your satisfaction, or lack thereof, of your Apple devices will probably inform your purchase more than a change in your power cord or the need for an adapter. If you're buying your first Apple product, the odds are you don't have any accessories to worry about compatibility issues.

The only thing that interest me, comparing existing products to rumored products, is the possibility of a smaller iPad. There are existing smaller tablets, so if the Android tablets suit your needs, they may be the way to go. But as someone who likes iOS, and already has a set of touring tools based around the operating system, I might consider waiting for a smaller Apple tablet if I was going to use it mainly for touring. But, while I expect to see a smaller tablet from Apple, it is entirely possible that it will lack the features that make the iPad such a useful touring tool to me: GPS and cellular data. Without those features, a smaller tablet wouldn't appeal to me. And really I am not in market to buy several tablet computers. It's not in my budget. And since I spend a lot more time on my couch than I spend touring, I would likely stick with the larger form factor of the current iPad, which seems to be the perfect size for most of my uses even if it does take up more than the ideal amount of space in a pannier.