Page performance and experience optimization is critically import - it's also a huge part of my reputation in the website industry.
Hence, because of this I moved away from Elementor 2 yrs ago and have been developing with Oxygen Builder as it is the best available - fast website development coupled with clean and minimal code.
Zion Builder is on par with Oxygen. It is fast - DAMN FAST!
One of the major things that puts Zion above Elementor is the slim code size it generates. Elementor creates lots of code and tons of DIV's. Zion's code is beautiful compared to Elementor.

Obviously, these sample templates were not identical at all, but it gives you a general idea of how fast Zion is without any optimizations performed.

There is no comparison between Zion and Elementor - Zion can run circles around Elementor.

However, there are not many prebuilt Zion templates to choose from, but my guess is they are building more. You can always view the Elementor templates for inspiration for your own custom Zion designs ;)

Also, there isn't much in the way of 3rd party add-ons for Zion. A quick search on CodeCanyon returns zero results.

Then again, some of the worst aspects of Elementor come from the poorly coded 3rd party plugins that can cripple your website performance.

Recommendation:
YES! Grab this deal now. If you like Elementor, then you will quickly adapt to Zion. And you will greatly benefit from the speedy pages it creates.