Actually, your concerns are pretty valid-As of Jan 1, 2013 the current 2 digit AAR Channels are gone. As in no more. (in theory-more on that in a minute) The standard channels are on the 25 kHZ bandwidth. Many RR's have already migrated over to Narrowband (12.5kHZ frequencies) in anticipation of the Jan 1 date, and are operating on essentially the same channels, only different, on the 3 digit AAR channels. In most cases, it's the same channel, only "narrow". If you usually listen on 52-52, they either have already changed over to 052-052, or will on or before Jan 1. As I said, in theory, you shouldn't be able to hear them. In reality, this narrow band thing isn't giving the bandwidth space that was anticipated, and I beleive you will be able to still hear, it may be just quieter, or harder to hear a bit.
So, if you are buying a scanner, get one that's narrow band capable, as the freq's tighten up, you may lose the ability to hear on the current 25 kHZ bands if you can hear at all now.
Now, that said, I would NOT buy one that's just narrow band capable-Go with one that's narrow band AND digital capable. (I don't know squat about scanners, I am assuming someone makes them, since they are making tri-mode radio's now) Becuase the bandwindth increase they expected just isnt there with this narrow band thing, the industry is expcting to see a movement to force it into digital radio before too much longer, making this whole narrow band thing just one big expensive bad dream. So, if you're buying anything, buy narrow band at the least, and buy narrow band/digital/tri-mode at best. That should suffice for this round of changes, and the next one that will probably come within the next 5 years or so as a best guess.
And, lastly? invest in some good ear buds to go with it. Drives me nuts, when somebody has a scanner/radio/gamepad/igalexy etc on a train, without headphones! Those sleeper walls are pretty thin....Just my pet peeve.