I bought my MBP just over a year ago and am already on my second battery and will shortly be buying my 3rd. The cycle count on this battery is 396 and condition is now only ‘fair’ so it is, to all intents and purposes not fit for use as it will only give me about 80 mins use.
If that was the case with a sealed battery I would be killing it in just over a year, that’s a very long way off the 5 years claimed by Apple.
I also travel a lot to Hong Kong and LA which means I have 12 hour flights to contend with.
Unless I fly business class, which I don’t, there is no power in the seats and even if I did, I’m not sure that the power in the seats is enough to take the 85w chargers needed for the MBPs. The Macbooks only use 65w so they wouldn’t be an issue.
I would be grateful for the extra battery power but would be forced into replacing the battery regularly, not an issue for me of course, provided I can get hold of them, but the ability to pop in an extra battery is something that I will miss… and when I used to travel with my iBook I used to carry 2 spares!
Like all generalisations there are ALWAYS going to be a number of people who fall outside them, I just happen to be one of them on this issue. There are a number of alternatives that can supply additional power but they are, quite frankly, ridiculously expensive and I wouldn’t entertain them, I’d rather watch the movies in-flight instead!

What I would really like to see is a full blown comparison in cost and technology between ‘like’ models of laptops, Mac vs anyone else. Case construction, Processor(s), hard drive, RAM, Port/slots, Video, maintenance plan costs/term and what is covered, internal component quality breakdowns. Even beyond to the OS: how much cost, how often updated, how frequently replaced with a new GUI. Security concerns. Include W7 and Snow Leopard. Review/compare legitimate bundled SW, and exclude the Demos. Cross reference functions like backups, ease of making WiFi connections, how much basic OS knowledge the end user needs to make (relearn) to make the computer function; the kinds of issues that would affect a TCO and the end user experience over years of ownership. Just the facts, no color commentary.

Where\when has this been done? I’ve looked long and hard but haven’t come up with anything close. Even trying to accomplish this across many blogs and various HW review sites is a frustration. Both camps provide entertaining ads and articles, but not the details.

I took up your challenge, i found a review of the Kia Amanti outscoring a BWM 5 series in crash test (we dont have Amanti in UK). I also found a UK review based on 30,000 various owners questionnaires which put the Kia Cee’d as more reliable than a VW golf and BMW Mini, shame you dont have Cee’d in US, I have a Kia Pro_Cee’d sport hatch (It’sreally rather good, I part exchanged a mercedes C for it) and a unibody Macbook 2.4ghz. I choose all my purchases on real value for money, not just cost or quality alone.