I own an Apex so I'm well aware there's mahogany outside of the RG series.
As far as I know the RGD is the only 26.5" scale guitar Ibanez offers; in Basswood of course.
MaxOfMetal (a sevenstring.org moderator), who knows just about everything about Ibanez, said this about Basswood:
"It sounds good.
It's very consistent.
It's lightweight.
It's economic.
It's widely available.
It's what Steve (Vai) and Mace (Bailey) decided would work best for the JEM/RG series in 86'. "
"Basswood has very strong mids and somewhat subdued highs and lows, that makes it very great for cutting leads through the mix, or even rhythms with the proper pickups. You'll find a lot of lead players choosing Basswood, such as Vai, Satch, Petrucci, etc."
If it ain't broke don't fix it!