Let's get a mahogany 7 string back in production first. Or perhaps even an upgraded 8-string, EMGs aside the RG2228 is the most plain RG in the current line-up. Including non-prestige! Don't get me wrong, I love my 2228, beats the hell out of the SC608 and the Intrepid! Perhaps you might want to look into a pickup change. Bareknuckle, Swineshead, and Lundgren all make super high quality pickups which sound amazing regardless of body wood.

Also, about body woods. Unless you're playing really clean or through a highly simplified all analog rig, you're not gonna be able to discern any significant difference, at least none that working the tone and EQ controls on your gear wont fix. From what I've found the wood used in the neck and how it's affixed to the body control more tonal characteristics in the tone, attack, ans sustain of the instrument.

Keep

and maybe we will see it come to live

I actually like the way my basswood body guitar sounds clean.

All I am saying is it would be nice to have mahogany version of the guitar. I thought more people would be in support of this instead of knocking down the idea (that's just one less option for RG 8 guitar players). All the artist that come to mind using custom 8 strings use EMG 808's no big difference there (see 09 Ibanez catalogue) I am using my 8 string with a Mesa F50 and Dual Rectifier Roadster through Port City cabinets (not a big gear problem ;). I find it strange that everyone that gets chance for custom 8 gets it in mahogany with EMG 808. It must not make a difference for the artists? I compared alot of Ibanez guitars that I own, and the mahogany feel so much more durable. It's easy to see why everyone would choose that over basswood standard RG 8 string.

I know that Dino at least has one RG8 with the 808 pups in it. And it all depends on the type of sound the artist likes and even if he has a endorsment deal with a pup company. But mainly it will depend on the sound an artist likes which pups he will choose to have on his custom RG8 he gets. Same goes for the bodywood. If he wants a nice custom bodywood he will choose any other wood than basswood, because that is just the same he (or she) will be able to get from a "normal" RG2228. I myself would also go for another wood if I had the choice, mainly because I can and that it will give my RG8 a more custom feel.

I do think that the RG8 would be great with a mahogany body. You can hear the different characteristics of different bodywoods. Just compare a mahogany RG6 with a basswood RG6 by running it back-to-back through the same rig with identical settings. You will definately hear the difference. However, I do agree MaxOfMetal that the amp and the pups have a bigger impact on the sound.
I also think that you should be able to get a good clean sound and a good metal sound from the RG2228. And there are aftermarket 8 string pups available, so if the sound is not really what you hope or want, look around and see if there are other pups that would give you what your looking for tonewise. On the Bareknuckle site they have some sound clips that might help you out.