My experience with 90 day online. The system was down for a few days last weekend. Did it at 00:15 the morning it was reopened and got the approval at 09:00.
I had a new (2 weeks) TM30 and a new address which caused me no issues. Additionally, my new report date is now 3 days before my extension expiration, which is correct. Some had expressed concern that they would fiddle with the date if the next 90 day was to close to expiration.
So nothing new here, I was slightly concerned about the new address and TM30.