Some lenders will look at your large limits as risky, and others might question why they should extend you credit when you have such high limits that aren't utilized already.
If you want to give up a HP, Chase can consider raising the limit on the CSP.
PenFed is a good place to find low-fee cards that can grow limits.
I think the comment about padding utilization is, that by itself is not a good reason to open another card, with the need to monitor and use the card. A better reason to add an account is if there is a set of features you can benefit from. You already have three revolvers, and the charge cards can easily help with utilization by running most charges through them.
The other aspect is you have three AF cards. I’ve got the same three and more with AF, but adding those accounts should be a decision for the card features, not utilization. At least, that’s how many of us feel. You can add any card you want regardless what anyone else thinks.
You can probably get an AMEX revolver, and build that up to a high limit eventually. The EveryDay card would earn MR points with no AF, EDP has an AF. The accelerator on those cards can help earning some more general spend points.
