Canadian Citizens CAN take a US registered car into Canada. Canadian RESIDENTS cannot taken a US registered car into Canada.

There will be no problem going across the border in either direction - just make sure you have a printed contract, as mentioned.

One thing about SLC - it's a franchise location with a horrible reputation for poor service and billing for damage if a single molecule is out of place on the car at return (sometimes billing multiple customers for the same damage they never caused, nor did the location ever repair even after payment).

They might have other terms about maximum distance driven from location, etc - it's best to call them and verify their location does not have any restrictions on where you can drive the car. Make a back-up res with another agency just in case.