Since she is under contract, RLH may not end up looking like THAT bad of a deal. If she has a robust plan already then it is max C$120 extra/mo to use it down there. There are cheaper plans available in the US, but do they have all the data and other features she already has, and how difficult will it be for her to change her phone number with all her contacts? The C$120 equates to US$88/mo, so her plan down there would have to be less than that (not TOO hard to beat, but keep in mind levels of service too).
Roam Mobility is a good option too at only $65/mo if the data limits are sufficient. Also note that for my family data usage goes WAY up when travelling; lots of online time staying in touch, so be sure of a robust data plan. The down side of Roam Mobility is that it ONLY roams on T-Mobile and we have experienced service gaps in Orlando area. With Rogers RLH we find we surf across several networks based on availability; mostly ATT and T-Mobile, but have seen others come up on my display, so less service dropouts.
For comparison, T-Mobile plans are US$70/85 for 3/20GB of 4G data (single line plan). 3G data is unlimited after the 4G runs out, but it is sloooowwwww. That price does not include Long Distance (calls to home) which can be free on Rogers if you have the NA dial option.