I'm thinking your rental should be more Brew on Premisis (BOP) unless there are legal/cost reasons that make off site rental better. Also you should provide gear and supplies to those who brew at home. My reasoning here is that the cost of the gear is fairly inexpensive, so after a bit people will buy their own, unless it is high end stuff. But you just suggested you were going after a 'new brewer' market for the rentals (post 20).
LD Carlson suggests that there are about 1 in 500 who homebrew in a given year, and that on average that berwer spends maybe $100 in stuff. Now 2 points on that number, 1. everyone here proobably brews more than that, but how many brew just 1 or 2x a year that don't read boards like this? 2. their data is about 10 to 15 years old at this point, so the numbers might be 1 in 300 or 1 in 700. In the US market, markup is about 45%, so for every $100 sale, 55 goes to the distributor and 45 to the retail store (again varries on product type and supplies, but working numbers here).
Wiki puts the population of Toronto (2011) at 5.5 Million. 5.5 million /500 is about 11,000 estimated customers, however I suspect that many of them like Emjay (poted at #19 and others) already have suppliers. But still 11K people who are likely brewers isn't bad. And it makes a good base for the LHBS. I was in Kingston once and they had a BOP there, seems like it was a good business (ok it was 20 years ago, so I've no idea really). But as I understand it the Canadian taxes on beer are killer, so brewing your own is very attractive. I also am aware taht space is limited, so what a BOP really does is rent space. Think of all the storage sheds around.
Anyhow, just some more thoughts for you.