Last night my partner was buying something and she said "Oh, I hate it when sites don't do PayPal". This surprised me, because I hate it when the only checkout option is PayPal - I'd much rather just use my normal credit card. But she explained that on her mobile, and when she's pushed for time, it's much easier to pay with PayPal than it is to dig your card out and enter all the details.
If I look at databases which offers both PayPal AND "normal" credit card (WorldPay) as checkout options, so far this calendar year the split is about 60% WorldPay / 40% PayPal. Which shows there are substantial numbers of people who actively prefer PayPal and who will use it even when other options are available. Activating PayPal as a payment option might well increase the conversion rate for spur of the moment mobile transactions.
So: I think it might be possibly be good idea to activate PayPal as a payment option even when you already have a "proper" merchant account, and please let us know if you'd like us to switch it on.
I'm also planning to integrate PayPal as a login option (alongside Facebook and Google+), and there's some kind of improved checkout process I need to have a look at too.