I have a new Sony 4K TV. I'm assuming the upscaling of 1080p content to 4K would be better than the Optik box is able to do. However it appears there is no way to set the Optik box to 'Passthrough' the native signal to the TV. In other words, if the signal is 1080p then send 1080p, if the signal is broadcast as 4K then send 4K. Seems like other cable providers I read about can do this but Telus doesn't offer the option, or am I mistaken and there is a way.
You can do a test to see if the difference is even noticeable. Set the Optik box to output 1080p on a HD channel and compare it to setting the Optik box to output 4K on the same HD channel. Maybe record a HD program for the A/B test so that the comparison is done using the same image stream. If you want to be scientific about the test have someone else switch the Optik output settings to do a blind A/B test.