Love my "pointies," and trying to design a somewhat bastardization between a Jackson KV2 and B.C. Rich Kerry King Signature V. I am also drawn toward slim neck profiles, such as the Ibanez Wizard neck (17mm @ 1st fret - 20mm @ 12th fret) and the Jackson "speed neck." Conversely, I am NOT a fan of guitar necks reminiscent of a roller coaster at Six Flags...
The neck will be constructed of a maple-walnut-maple lamination (roughly 6/4 - 1/4 - 6/4), and the grain orientation of the laminates after glue-up will look like
\\\\II////
In addition to these precautions, I thought it would be wise to add additional strength to the neck with the use of supporting or stiffening rods. It seems that there are two prominent types of these supports:
1) KTS Titanium Neck Support Rods
These have been frequently used by Ibanez over the last couple of years, especially to strengthen and support their VERY thin "Wizard" necks. As a side note, according to claims made by both Ibanez and KTS, the properties of titanium will markedly improve the resonance and tone of the instrument (although I have not seen any empirical studies supporting this claim. IMHO, subtle changes noticed in the tonality and resonance would qualify more as SUBJECTIVE observations, rather than OBJECTIVE).
2) Carbon Fiber Stiffening Rods
I first saw these available from StewMac, but I have since seen them offered by a number of other luthiery suppliers, such as LMII (IIRC). Carbon fiber is well known for its significant strength and stiffness, while remaining very light-weight. While I cannot remember for sure at the moment, I believe the use of carbon fiber neck stiffening rods have also been attributed with changes to the tonal qualities of an instrument.
As I would like to construct a thin, wide neck similar to an Ibanez Wizard neck, stiffness and strength are important characteristics. Also, the scarf joint of the headstock should meet the neck roughly at the 3rd fret. I have heard from several people that scarf joints AND slim-profile guitar necks are substantially more prone to breakage and/or serious damage. My thoughts are that using the titanium rods would greatly reduce the likelihood that the neck would break at the scarf joint (although, the carbon fiber may accomplish the task equally well). As for pricing, I have seen the KTS Titanium rods on eBay for $20/ea. While I do not remember an exact amount for the carbon fiber stiffening rods offered by StewMac, I think the are similar in price.
In closing, I am very interested in hearing from anyone with insight into either, or both, method for supporting and stiffening thin guitar necks. Are there any differences noticed in the effectiveness at restricting or reducing any neck flexing, twisting, or breakage.