I would generally say don't bother with Applecare, portable or not. It's a rip-off. For it to be worthwhile, something has to break of its own accord in either year 2 or 3 that is more than $300 to fix.
You're far more likely to drop it or have it stolen. Applecare won't cover you for either of these, however hard you try.
Ok, so you may be unlucky and have to replace the screen or something, but there are reuptable companies that can do that for not terribly much more than Applecare. However, the chances are NOTHING will go wrong in years 2 or 3 and so you will have paid the money. Sure, not getting it is a gamble, but one with very good odds. Even Apple's statistics show that too.