Public Mobile's 3000kbps "3G" data rate equates to almost 1.3GB per hour, maximum.
It might not be enough bandwidth for xCloud service, unless it supports lower quality and lower resolutions.
xCloud apparently isn't encoded in a format which Telus Wireless Video Optimization currently supports. (Telus uses an Openwave/ENEA Media Optimizer which apparently does have Encrypted Network Traffic and Encrypted Video Manager extensions, but latest releases do not officially support xCloud at this time. They do explicitly support YouTube, Netflix, Prime, and other encrypted media streams.)
This means that xCloud content may be unoptimized when delivered to your device, eating a lot of data. While YouTube/etc content is optimized (transcoded down to the maximum display limits of your device) so the same video consumes a lot less data.
Using cellular data to watch movies would be a very costly way to get very little xCloud entertainment. Any other kind of real internet connection would give far greater data bandwidths at far lower per-GB prices. Maybe you don't mind paying $40/month for a few hours of showtime, but there are better options.
