I did some research on aluminum guitars a while back and found some interesting things you should really think about. The biggest issue is that the thermal expansion of aluminum is about 100 times greater then that of wood. So staying in toon when temperatures are fluctuating is going to be a nightmare. I know my wood guitars have issues just from warming up in my hands after 15-20 min on if they've been in a cool room I can't imagine that magnified by 100.
An interesting point, Martin; having worked with alum. of various grades for the past 10 years I'm aware of the expansion characteristics you mentioned and I've seen alum. "grow" with very slight increases in temp. The average coefficient of thermal expansion for 7075 aluminum (68° to 212°F) = 13.1 x 10-6 (inch per inch per °F). Looks like the body mass of the instrument itself would dissipate the induced body heat. Ambient temperature will have the greatest effect on the tuning of the instrument and seems like it'll be a constant battle to keep it right. I wonder if I could manuf. after-market heatsinks or aux. cooling fans for these babies. However, finding a suitable place to mount them may pose a problem. The designers should have installed a radiator in that thing.
Consider that Aluminums thermal rate of expansion is probably a hundred times greater than wood, this thing could go out of tune when the breeze blows.
Here's another thing nobody thought of, if you heat it with a torch it may burn your hands OR may melt as opposed to burning. Also, if you take it into the shower it may get wet and ruin the pickups!!!!
Travis Bean made alum/necks but they put wood inserts in them as players found that the metal chilled the muscles in the hand and caused cramp, specially in cold venues, Valeno' ? veleno, made all metal guitars with pointy heads and chrome or gold plated finish , The Talbo's still come up on e-bay from japan and make good money.
My good friend Frank had a Kramer guitar that had an aluminum neck with wood inserts. The guitar could sustain forever but as soon as you got it under stage lights it would go out of tune. It made for a great studio guitar but playing LIVE with it was out of the question.
If what you're looking for a very stable neck, here's an option to consider that might work for you with a mod to your current axe... http://mosesgraphite.com/catalog/Electric_Guitar_Necks.html