What is your recommendation on upgrading a Linn LP

Well, since the OPs 3 preferred options are all Linn-based I'm going to stick with that question and keep it relevant. ;^)

The LP12 has the distinction of being the (only?) turntable that can be built from scratch using readily available non-Linn parts. Not only that but there could be massive number of permutations possible through alternate combinations!

Lets look at some options -
- Origin Live motor kit (highly regarded vs more expensive options)
- "Hercules II" (mentioned earlier).
- Cetech sub-chassis (again very popular & relatively inexpensive. Not sure if this is available now but Linn are countering the aftermarket sub-chassis suppliers with their Majik (£300) & Kore (£750). Both are way cheaper than a Keel.
- RubiKon = aftermarket competition for the Kore.
- There is also the TigerPaw Khan top plate upgrade. Bit pricey so I'm not sure I'd entertain that one. I'd consider a "BooPlinth" first.

Speaking of the "BooPlinth" (a continuously NC machined bamboo variant) which the former editor of HiFi+ Roy Gregory was ecstatic with. Roy, you may remember, spent a fair bit of time in that capacity doing VTA "roadshows" to illustrate the benefits of accurate VTA (during a time when very few arms had this capability) using a VPI with Tri-planar. In fact Roy said in a recent issue of HiFi+, "It's been 30 years since I last owned an LP12 but all of a sudden I'm taking the idea seriously again..." such was the impression the BooPlinth made on him.
His review is an interesting read and he is convinced it is a real game-changer.

The BooPlinth is not the sort of thing you'll see heavily advertised as the 2 guys who created it barely managed to scrape together enough money to get them manufactured(!) - so not much profit in it (and certainly not enough for "payola").
It's not cheap at £1650 so some serious decision making required there... (but I know one or two folk keen on buying it already)

Finally there is the question of implementation. Getting a franchised dealer to upgrade the T/T with aftermarket parts on your behalf might prove difficult but there are plenty of skilled amateurs/pros, I'm sure, in your neighbourhood who might offer to help if required?
All the best, whatever you decide.

Well, since the OPs 3 preferred options are all Linn-based I'm going to stick with that question and keep it relevant. ;^)

Suggesting a better option is completely relevant don't ya think?

Firstly, that depends on your subjective definition of "better".

Secondly, turntable design is not as straightforward as ya might think so ya may be astonished to know that your "better" (insert as applicable) design has flaws.
(This also means that the LP12 has its own flaws).
If we're referring to VPI(?), until recently, their "engineering solution" to the problem of anti-skate was to twist the tonearm wires if required...
It's great when a manufacturer can omit a moderately costly engineering feature then advertise this absence as a "strength" thereby saving himself money but charging you more for the end product because it's "stronger". It's a win-win.

Thirdly, I'll leave it to the Schatzman to decide whether your advice is relevant or not.

Fourthly, if you are a particular turntable dealer or manufacturer who has infiltrated a Forum I am sure it's entirely relevant.

Add a Linn Itok LVII tonearm and a Hercules power supply and sit back and enyoy your table. While you at it, give your table a good tune-up; new oil, springs, gromets,etc.

I have a friend with LP12/Valhalla/Ittok and a top VPI. Guess which one gets more involved?