most important questions is how much is your business expenses/gst/vendor payment. If it is a considerable portion then biz black is better.
With that kind of usage paid or fyf wouldn't matter much. Do note that unlike infinnia, diners cards don't give rp on renewal.
if your business spend isnt much, you should push for infinnia. Your spend/nrv also justifies that.
And ask for upgrade not a floater. If you take floater you can't take add on. Have to pay bill separately for both cards. If you pay excess on one card, it won't be adjusted with other's bill.