Stewart is a fantastic company. That's the first thing to be said. They have a wide range of products and they can satisfy the need of EVERY theater in the world pretty darn easily. From the largest screens you can imagine to some of the most unusual setups feasible with a ton of screen surfaces and options that'll blow your mind.
Carada doesn't do this. They give you one type of screen: Fixed frame. They give you two frame options: Precision and Criterion.
Then they do things brilliantly. Their MSRP on the Criterion is less than the COST of similar Draper and DaLite screens! The surface is often compared to Stewart and their build quality is easily in line with what the best companies are giving you are two to five times the price.
Would you see an improvement with Stewart? Perhaps. Maybe, just maybe, if you put the two screens up one after the other in quick succession and you were looking for it, then you would see a VERY marginal improvement. But, beyond that, I would bet that almost nobody would see that improvement.
Better ways to spend your money?
1. Get a few replacement lamps for your projector - then USE THEM! Lamps seriously start to dim after about 1,000 hours of usage. Many people who have projectors don't realize how incredibly the fall off of light output from a projector is until they put a new lamp in. Then they stare in awe as their projector is revitalized to a near brand new image quality! It is truly amazing.
2. Get your projector ISF calibrated. If you have not done so, a good ISF calibration of your projector can do more for the quality of what you see on screen than many other improvements. It is not always worth the cash, but it will likely do better for you than the thousands you will spend on a new screen.
3. Paint the rooom (pay someone to do it!). Ambient light, especially ambient light do to reflections, is a serious way to degrade image quality. Why would you fight this with some special screen when a darker coat of paint, with some added lights in the room can maintain 100% of the room's brightness when necessary, while reducing reflected light during critical viewings significantly. This can be CHEAP if you are willing to do the painting yourself!
4. New projector! Well, maybe not for the price of the screen, but I don't know what you have now and what you might consider as an upgrade, but there are some phenomenal projectors coming to market now that can seriously up the overall quality compared to many of the older projectors.
FYI: I own a $3K tab-tensioned motorized Draper screen. It works well for my application, but if I were to ever buy a fixed screen I wouldn't have to think for a second: Carada has proven itself not just in desgin and build quality, but also with unbelievable customer support and an ability to communicate that the three biggies just can't touch.