Hi!
With my prior company, we were the first in the DC area (this is quite a while ago now) to partner with American Express when they ventured into the Multifamily World. You are not allowed to pass the fees along to the resident when you partner directly with AmEx. As we were an early adopter, we received a marketing edge by doing this, and typically saw higher rents and occupancies than our competitors (and when analysis was done, the renters paying on recurring AmEx payments were living in more expensive apartments than their counter-parts and tended to stay a little bit longer). I can't say that this was purely due to allowing recurring AmEx payments, but do believe it played a role (especially because credit cards were not yet widely accepted at this point). We had 30-35% of residents at the communities where this was offered signed up for recurring payments with AmEx (making life easier for the onsite team).
Fast forward to the recession, and our investment partners were no longer willing to eat the fees (which were substantial as most of the communities where this was offered had average rents of over $2000 per month). At this time, said company went to one of the 3rd party industry vendors to allow for online payments. With this set-up, for credit cards, the resident pays the fee. Online payment adoption was high (with ACH being the most used), however, credit card payments dropped to under 10% as residents did not want to pay the associated fees (even if you are getting points/mileage....who wants to pay over $50 more per month (again, remember the rent levels) to get points?).
Allowing credit card payments can be a great amenity, and if you are able to absorb the fees, adoption can be high, and make your life onsite easier.
Regarding the comments about "watching" residents who pay with credit cards, you need to look at your market and demographic. Broad statements can't be made about who pays with credit cards. I work in the DC Market, and our customers like the recurring payment options (credit card or otherwise) because they are busy and it makes their lives easier. I use my credit cards for as much as possible so that I am getting points along the way (and even right out of college, I've never gotten myself into trouble with any kind of credit card debt)and don't have to worry about carrying cash around with me.