I hope you don't buy TOO much real estate using those assumptions, at least not in the US. The OP used a rent figure of $1,300. I can't speak for rates and terms in Canada, but in the US, the OP is going to put a minimum 25 percent down and pay at least 1 percent premium over the owner-occupied rate. Since 30 year fixed rates for owner-occupied properties are 4 percent, I will use 5 percent. You assumed a purchase price of $110,000. His principal and interest payment is around $443.
OP pays utilities, not a good thing because they are a big percentage of the expenses and there is no incentive for tenants to conserve. Adding up all the expenses, including utilities, vacancy and collection loss, property taxes, insurance, and repairs and maintenance (including pro-rata capital improvements) gets the expenses up to a minimum of 50 percent. That seems low with utilities, especially in a cold climate. If the pro-forma from the seller indicates 50 percent, your actual expenses will be higher. Seller expense statements reflect best case scenarios, and that's putting it nicely. With utilities and reasonable taxes, say 55 percent as a best case scenario. $1,300 x 0.45 = $585 is the net after all expenses except the mortgage. The net income after paying the mortgage and all expenses is $585-$443. That's $142 a month, or $1,704 a year. If The OP invested the down payment of $27,500 and the closing costs of $5,000 for a total $32,500, the hypothetical cash on cash return is $1704/$32,500, or around 5.25 percent.
If the OP pays cash, the net income is $585 x 12, or $7,020. Dividing that by the all in amount of $115,000 gives you a free and clear cash on cash return of around 6.1 percent.
What Praxis is saying is after you allow $130 (10 percent) for property management and $130 (another 10 percent) for taxes and insurance in your mortgage payment (assuming you could get 80 percent financing with 20 percent down on an income property), you could earn these spectacular rates of return if you had no vacancy or repairs. Not only has he not included the utilities, he's assuming 20 percent expenses net of utilities, which we already know is not achievable. He then allows you an additional $3,720 a year in expenses, or $310 to get to a 13.5 percent return. The trouble is that's 43.8 percent expenses, which we know is low, and the conclusion assumes financing that is likely not available to you.
I'm all in favor of buying and operating rental real estate. However, the numbers have to be accurate, and they have to be analyzed carefully. Small changes in the assumptions can have a dramatic impact on your return and can push you from cash flow positive to cash flow negative. There is risk here because you do not have a good handle on the numbers. In your shoes, I would do more homework before I started writing checks.