It's also my understanding that the rent-to-own scenario can be riskier for new owners, too. If something should happen and you can't carry through on the purchase, you may lose the amount you've paid toward the downpayment every month.
I guess from the standpoint of an Exclusive Buyer Agent who doesn't ever have conflict by representing the seller, I would ask if you have a representative looking out for your best interests? It's hard to know what's really best for you without being close to the transaction.
Ultimately, if the finances are close, it's usually better to make a decision based on the house itself because you'll be happier in the building you really want, rather than feeling like you settled. If it was really close and you really liked the houses the same, of course the financial would tip the scale for you. I would encourage you to make sure the financial decision is sound and look at how you'll feel in this house longer term as well as how it may impact you upon resale.
Further, financing is getting tighter and interest rates may go higher, so the house might very well be less affordable next year than it is today. Also, you get tax incentives for mortgage payments that are substantially higher than the incentives for rental payments.
I don't know if I would ever counsel a buyer to put significant expectation in a rent to own... especially in this market. If losing the house isn't a problem and/or the rent is in line with what you'd pay to rent it normally (outside of a rent to own situation) then there's no loss. Otherwise it sounds like quite a risk.