That's interesting... I guess Apple can break their own rules occasionally! (or ... it just slipped through and nobody noticed)
The apple success page is quite a good idea, once DHCP request completes and a WIFI is linked up it visits that page. If it gets back the standard response it lets you continue, otherwise it pops up the browser that lets you log in to the commercial access point.
I guess they could leave the GPRS working and servicing requests right up until that success page returns a positive, but actually it flips everything over which is annoying. So if you cancel the popup, and then go browsing - you get straight back to the WIFI captive portal again. Its annoying that it will remember the fact you once tried to connect to a commercial wifi and will forever after connect you back up to it again ... i often go into my settings and 'forget' all the networks I don't regularly use.
As you said... we digressed somewhat here! Back to topic....
It sounds like we are safe to conclude that the built-in GPS is pretty good for most purposes, but drops out at altitude and also in some weather conditions. Certainly my steam powered Garmin 496 has a better link. I will be buying an external one as per Peter's recommendations and hopefully that closes the gap, not least because you can put it on the top of the panel which should give it a slightly less obstructed view of the sky.