I can't get a wood bodied Benz anymore

Honestly, a re-tip only sounds like a pretty good option. I also think the original cantilever is key to maintaining the original sound. Recent reports on SS's turnaround time makes it sound pretty reasonable. What (much) have you got to lose if it's your best (and an affordable) optional to try and maintain the sound you like?

I have an old Koetsu Onyx Signature that I'm considering doing a re-tip only on.

I had Soundsmith retip a Benz Ruby earlier this year. The turnaround time was less than 4 weeks. I haven't installed it yet, so can't say about sound quality.

If you get it retipped, and by this I mean have the stylus replaced, as Drrsutliff states above, it should not have a change to the sound assuming you use the same stylus profile.

If you change the cantilever to a different material and replace both the stylus and cantilever then it would have an effect on the sound.

Soundsmith usually turns around items in 6 - 8 weeks. You shoudl ask them directly. I have never heard of or had them take 6 - 8 months to repair an item.

Cardas myrtle wood is a benz ruby in a myrtle wood body. It is still available.