What kind of Hilton is it? I haven't seen anyone have luck getting a retention offer on the Hilton Biz. There was a DP a few weeks ago about a retention offer on the Surpass of either a $100 statement credit or 20k Hilton points after $2,500 spend in 3 months. The Hilton Honors or Surpass could be worth keeping because they're often targeted for upgrade offers.
I was having the same dilemma about what to do with the Biz Green. I can't read the RAT's mind, but my own reasoning is it's better to cancel a card I'm not using and spend on the cards I still have open than to keep a card open and put little or no spend on it. Amex values spend because they rely on interchange fees a lot more than other issuers. If I can get a retention offer or an upgrade offer to a card that has some use to me for the next year, I'll take it over closing it and keep the card open for another year. The Biz Green was barely getting any spend, and that's after I threw some subscription charges on it. I upgraded it to a Biz Plat, figuring the $10k MSR over 5 months will keep me spending on it for the 50k MR. Like I said, to minimize my net fees, I should've either jumped a week sooner for the Jan-June Dell credit or waited two months to avoid the prorated AF.
I *think* the my comment that you quoted is how the AF would work in an upgrade/downgrade situation. Calculating the dates when the fees prorate is tricky.
ETA:
@SBWB48 says it looks like Amex is charging the prorated AF based on AF posting to AF posting vs. actual anniversary date.
https://www.disboards.com/threads/i...t-page-for-addl-details.3729982/post-60785814
I do plan on canceling my original Biz Plat when the AF posts later this month. Then I'll have recently canceled the Hilton Biz and Biz Plat, and I don't know what that'll do to me pop up-wise. My last Amex app was in June for the BBP. I'm about tapped out on Amex biz cards, and don't plan on opening any Amex personal cards for the rest of this year to stay at 4/24. (Another slot won't open up until next April.) In the meantime, I'm spending a lot on my Amex Gold, BBP, and putting consistent spend on my Plat and new Biz Plat, and to a lesser extent my BGR, which I'm looking to upgrade to another Biz Plat in December.
Basically, I'm doing what you're thinking of doing. Upgraded the Biz Green to a Biz Plat. Going to close my original Biz Plat. Keep spend up on my Amex cards, and hope I don't get the pop up.
Oh, I do think that there's something to length of your relationship with Amex, like
@platamama said. I haven't gotten the pop up yet, but I've been an Amex cardmember for 8 years so it's not like I'm a grab all the bonuses and go kind of customer.