if (when) the buyers stop paying, you can go to court to evict them and you can sue them for the breach of the contract. you would AVOID any of the formalities or costs or delays involved in foreclosing on a mortgage. its annoying, expensive and takes time, but much less so than if you sell the house outright and give the buyers a mortgage.
you state the most obvious "con" is in your question. if the buyers are not paying rent now, what would be any different if there were a sales contract? another disadvanatage is that you must continue to own the home, and manage all of this until the contract is closed. (i have had some clients sign 12 month contracts, others for 2 or 5 or 10 years). again, not substantially worse than managing the property as a landlord, but if you had a straight up sale, you would get all your proceeds up front, one lump sum, and you can wash your hands of the whole thing. its just neater and cleaner that way.
installment contracts of this sort are really, almost always, a transaction of last resort for buyers, more so than sellers. way too much risk for the buyer. i have only known one buyer in 23 years who actually completed a transaction. every other stopped making payments for one reason or another and lost everything they invested in their deals.
One immediate con I see is that your renters don't seem like a very good credit risk (behind on rent, poor credit, etc.) Will you be put in much of a bind if they continue to be late on payments? Another risk is the valuation of the property. Make sure you are getting fair value and can agree to this with the buyers/tenants.
The 'pro' side of the equation includes the fact that you may have buyers interested and ready to go. In todays market that is always a plus.
Depending on the location and income, a local Realtor should be able to put you in touch with investors interested in your property. As a campus town Champaign/Urbana has a strong investor community. If you are looking for options on the sale side drop me an email or contact your local Realtor to figure out what choices you have.
Good luck and by the way, if you consider selling on contract to your tenants get a good attorney! :)