Didn't we just learn recently (months) that there are NO replacement sensors for the M8 and M9 cameras. (I suspect this created the body inventory for the Monochrome M?????)
Are there parts on the Noctilux that have a similar risk of unrepairable based on considerate operation of the lens, and no parts repairable to fix it. Don't consider droppage in each comparison.
When the bloom comes off the rose on the M9 (your inclinations) will you regret no longer having the Nocti (your words "I use it a lot")
Have you any anecdotal information on the use of the Nocti on the M9, and will you regret getting the depreciating M9 and Not having the Appreciating Nocti to use on said M9, if that's likely?
Will you regret the exchange, if you have 10 shots with the Nocti during the exchange, on the M9 if possible, and finding there is something magical and not attainable by any other combination.
Will you publicly admit to being an idiot if the deal is simply very bad for you?
Has any Leicaphile ever done any thing with any Leica body and lenses of this nature, that you heard tell of... any similar anecdote that has resulted in it being all wrong for one of the participants, AND DO you have a gut feeling at any level, that you would get the short end of this deal?
At this point in time, how may M9's are there, or shortly will be in the market for acquisition...???
Now, same question about the Noctilux?
Does the other party exhibit great nervousness or anticipation about this transaction, or any indication that he/she is under terrific stress about this deal falling through?
Let's see.... OK, I know I can think of other questions, but I may have given you enough food for thought to kill one night's sleep here? I'll post again tomorrow. I know it's not all about the money, but it should be.
Oh, and by the way NOT ONE of the four items you mentioned is MINT.
The best any of them can be is Excellent Plus. Mint is unopen, sealed, not used. Now they may qualify for the trite phrase "Minty" coined for eBay, or they may be "collectible" only by some standards.
Good luck pondering. Clearly no one posting here has offered up a solution for you that won't have you wondering for a couple of years.
Optimal, keep your stuff and buy the best, least expensive M9 you can buy. You can obviously afford it.
Your heirs will thank you... a wife, a brother in law, a son/daughter, nephew/neice...
Envision any one of them shooting this equipment on a trip to a family reunion in Pasadena.:bang: