I've long thought that raising fares is a good idea, provided subsidised passes are available to those of lower income.
I have no issue with subsidising overall transit costs, whether it be through gas taxes or property taxes. But the fact I am subsidising the transit rides of people who make well more than I do (or even comparable wages), does bother me. Those who can easily afford paying the actual cost of the service should be paying closer to that cost IMO.
I have not seen any serious studies done on it, but would expect that an increase in the cost (provided low wage earners do not see an increase) would generate only a small reduction in the amount of users. Considering the cost of operating a late model car is ~50 cents per kilometre and how expensive parking is in some places, it would take a huge raise in transit prices for it to become the less affordable option. I have the shortest commute of anyone I work with, have free parking and taking transit still comes out close to $3000/year cheaper than driving.
Unfortuneately, due to where I work, taking transit would add 45 minutes to each side of my commute. Since I value my time, I have not made the switch to transit yet. But, I am exploring job options and you can bet that if I end up working somewhere where the transit options make sense, I'll be on transit every weekday morning.