1.The latter - they're resistant to heat and wear under heat (the one used up to 490 C). Not very important in our case, as No one is going to use N900 in such circumstances, but if you drop your device into fireplace, you at least should be sure that your backcover won't lose colour

As for heat dissipation, the effect is negligible, and won't affect properties in any measurable way as compared to anodizing. Of course, bare aluminum will always be a tiny, tiny bit more effective at this - but, it won't be bare for long, as it will oxidize on it's own (just in non-uniform layer, so without as much added scratch-resistance as with anodized or lacquered surface). So, for our intents and purposes, no change here.

2. Indeed they're insulators, but not much more than the layer produced during anodizing. After all the latter, is alu-oxide, formed in layer with certain properties (very small pores, that are used as residue for a special after-anodizing dye, BTW) - not great conductor, either.

But, in our application of whole body replacement, it doesn't matter - for the radios, we have a thousands orders of magnitude bigger "problem" with the *conductor* used for body (that is, Alu). Incidentally, conductor act as shield, in this case - even on it's own, but even better when it's grounded (at the very end to battery - not real ground, but still). It is the case for N900's metal parts (border around screen, back of screen...), and will+must be the case for body replacement.

Due to this, in full body replacement, antennas will get "re-delegated" to the outer side. Think N950's antennas, just without N950's poor radio performance (as they have failed with the quasi-coil antennas).

Of course, there is still the port for connecting external antenna for N900 that is a crucial (read: must have) part of body replacement which will allow to get absolutely superior radios performance in special situations - but I'm absolutely sure that performance of internal antennas is no less important, for everyday use. Won't neglect that part, that is for sure.

Side note - I was *very* tempted to create complete new internal fractal antenna, that could get integrated into back part of body replacement. But, designing one that will work well is hell of a task, with much, MUCH testing and trial&error (even if using antenna designing software, like 4nec), so it would delay body replacement part considerably (it could take as long as doing everything else...). So, it's idea that I'll try someday for my own, slowly, and report if I succeed

/Estel