I had 2 carts retipped- one by Soundsmith and one by VAS and I left it up to them. Both times they recommended replacing the tip only and they both came out great. So IMO, use a top-quality person and take their recommendation. They know what works and they want you to be satisfied when you get it back.
There should be no concerns using Joseph Long, I have followed it for many years now.
I also know a recent build carried out by him on a Kontrapunk C, where new parts are added, has blown the new owner/user of the Cart' away, it is claimed by the individual who informed myself, that it is now preferred in use over a much more expensive Cart'.
His Work is going all over the World and here in the UK, the Boron Cantilever with a FGS is a recommendation that can be seen regularly and those that adopt it are very complimentary in their appraisal.
I have become a fan boy of Ogura Vital Styli with a Beryllium Cantilever, I have heard this in comparison on same TT>Tonearm as a A/B to a similar Cart' but much more expensive from the same Brand/Family with a FGS added to the Cart' and I am more than happy with the choice I have made.
I have also A/B compared my Cart' in the same manner as above to a Cart' from the same Brand, with a Boron Cantilever and Ultra Polished Replicant Styli, and again am very pleased with the choice I made.
Sending back to Lyra is an expensive option, but you will end up with a Delos. Retipping with Joseph will cost $600-$700, but you will have a different cartridge. I have had more expensive cartridges retipped by VAS and to me it did not make a difference - it was good as the old one. A lot will depend on how much of a purist you are.
An "upgrade" is nebulous because the cartridge was designed as a complex interplay between a very specific set of parts. A ruby/sapphire rod is a lot heavier than boron; I would avoid that for sure. The exact stylus cut is probably far less impactful than nearly DOUBLING the specific gravity of the cantilever material, and both Gygers are very good. As others pointed out, retipping on the existing boron rod might be a good way to go, but I don’t know if or how that might compromises the mount/bond (which IS important). Lyras usually use a very clean looking interface mount and I doubt that’s what you’ll get unless you do an exchange with Lyra themselves.
My Lyra Kleos is currently at Soundsmith for the second rebuild. Instead of getting just a nude contact line retip like the first time, this one is getting a boron cantilever w/CL. I am not a puritan and I fully trust Soundsmith. Plus since I now mostly stream I don't care of keeping the Kleos in its original configuration in order to sell it down the road because it's gonna take me well over a decade to get a thousand hours on it. It used to take me less than two years prior to streaming. And who knows if I will still be kicking in 15 years...
Can't wait to see what Soundsmith can do with it.
@baylinor You have stated " I am not a puritan and I fully trust Soundsmith "
As said by myself in a previous Post in another Thread about a Cart' Rebuild,
' to have a Trusted Workmanship is a Luxury '.
There is nothing to suggest the returned Cart' will not be impressive, the Boron Armature will bring something new to the presentation.
Will it be enough the put a 1000hrs of usage on the Cart' in a few years 😎