And yes accounts are linked
The transfer takes place immediately. If you require assistance with a transfer you have made, please submit a Support Request under the "Help" tab and we will be happy to look into this for you.
It's definitely not immediate. I transferred 10,000 points from SPG preferred guest to be 30,000 points on Marriott Rewards this morning. The 10,000 points are gone, the email confirmation that the transfer has happened has been received, but no sign of the Marriott Reward points. Frustrating because now I have reduced my SPG balance below what's required to book a more expensive city centre SPG hotel instead.
I can now confirm that in my case, it was a 2.5 hr process, in case helpful to anyone else...
I commented about the same thing yesterday. The transfer showed up immediately on the SPG site, they sent me an email saying the transfer had been successful, but on the Marriott site nothing has changed. So, for me, it's been about 22 hours since I transferred points and there is no change in my Marriott points count, either the regular points or the lifetime points.
Retrieving data ...