On the phone with UK Rep, have old cat 1-5, asked to convert to NC5, she quoted me 65k points to convert to NC5. Is that the appropriate value? Per Wiki I thought it was 45k?

Please read the wiki which as the value of each level and how much additional you would need to upgrade. In your case it is 60K.
45K is the RESIDUAL value of your OC5 when you cancel the cert.

When you want an NC5, it would cost you 60K EXTRA to come up with the 105K residual value of the OC7 that maps to NC5.

Use the codes to lead the agent.

60K. The activity shows -105K for the new partial package and then a +45K from cancelling the old partial package

If I'm reading this right, it seems that any OC to NC conversion will auto-refund the 30k difference for OC6, OC8, and OC Tier 1-3 holders, but is there any successful reports of going from OC Tier 1-3 to NC 7?

Originally had 2 OC Tier 4-5s, attached one and downgraded the other to an OC Tier 1-3 before August last year. Now want to pay the 120k difference for NC7, but am wary of turning Amex MR into Marriott points unless conversion can actually be done...

With the current state of affairs, anything is possible but nothing is guaranteed.

Call them and ask, if the only objection is that you don't have the required points then you have some confidence, if they refuse to even entertain the concept then your stuck.
I'm about to give it a go myself this week so if you have the option to wait for some feedback I should have something to share, for me it's OC7 to NC7 that I'm going to attempt.

A few days ago when I asked, was told no "upgrades" allowed, but can certainly get 30k back as a OC Tier 1-3 holder when moving to NC6. Have not HUCA but noticed in the Wiki the term to use should be "convert", will try again soon

And do not let the excuse you do not have enough points stop you. You can order TP certs without having all the points needed and your points balance will go negative. You may never find another agent willing to entertain the idea of an NC7 conversion so if you find one go ahead and do it even without enough points and your balance will go negative but the order will go through. This happened to me going from an OC8 when the agent mistakenly ordered me an NC6 and my balance went to -30k points. I do not know if there is a limit on how much you can go negative but the system used to allow it. Works like a points advance.

One thing I would ask if you are successful in doing this: do not have buyer's remorse later and call to get it refunded because you decide it costs too many points. If they start looking in to how it happened they may institute some new measures to prevent it.

that's what the wiki says - it's not clear you can only get the refund at the same time you convert OC to NC. What i was hoping is was to move the OC8 to an OC7 cert for the 30k refund first, and then convert to a NC5 later.

Although the details are different, I had the same result. I wanted to convert an OC8 to a NC6, but wouldn't have the required points until a CC bonus posted. I found an agent who said it was possible after the points posted. She was nice enough to try the trade which left me with a NC6 and a points deficit. Since up-conversions are never guaranteed, I might had lost out if I waited for the points to hit my account.

It is very clear - because OC table no longer exists.

You cannot move OC8 to OC7, or put it this way, the table for OC is deactivated in the system therefore you could not do this. The only way is to convert to NC and get the refund in the process.

Besides, what exactly you try to accomplish by this maneuver?

My OC8 cert is currently attached right now so I would like to get the refund and then convert if I don't end up using my original reservation. But it's fine if I can't do that.

Read back a few pages, it is just recently reported that when you detach the OC from the existing reservation, the OC returned to your account without ANY change, i.e. same category (the code stays the same) and same original expiration date.
Then you can decide when to convert it to NC, when the refund would / should automatically return to your account.

Just make sure you detach the cert first, before cancellation your reservation - if you still want to keep the cert.

I just spent the past hour reading recent posts on this thread.
Thank you all for sharing your experience, as someone who wants to do an OC to NC conversion (with a cat upgrade), I found the information here very valuable.

One thing I'm still a little confused about is this: once you receive a NC from an OC (equivalent cat conversion without any upgrades), can't you just pay additional points to upgrade the NC you received to a higher cat NC, where the points required would follow the new Travel Package table on https://www.marriott.com/loyalty/red...el/packages.mi ?

I'm not sure why everyone who wants to do an "upgrade conversion" is trying to do the upgrade when the OC gets converted to the NC.
Wouldn't it be easier to simply get a NC that is equivalent to the OC first, and then call again to upgrade the NC you have to a higher category NC by paying the difference in points required?