Since it is rated for 35k gallons and you have a 27k gallon pool, you will need to run it at 100% like 19 hours a day. It would have to be a pretty good bargain and even then if you are not already running your pump that long take a look at how much extra electric that will use. Also check to see how much the cell replacement costs as it lasts around 5 years. Less if you run it more often like you will be.
This SWCG is end of life and on Jandy's archive pages. The replacement for it can be had for around $700. What are they trying to unload this one for?
$850 CAD. But you're all correct - its to small.
https://www.jandy.com/en/products/water-sanitizers/truclear
Again though, it is really too small for your pool. We usually recommend double the size. I have a 29k gallon pool and run my 40k rated SWCG at 55% 24 hours a day.