Convert Custom Theme to Bricks & Vice versa

I’m trying to understand if gradually adapting a existing custom theme to Bricks is a good solution.
Having some pages built in page-whatever.php and changing them to a Bricks template.
Or vice-versa, if its problematic to build a CPT page template with Bricks and as the complexity of the queries rises, change it later for a cpt-custom-template.php page?
And, looking at the future of WP, is it advisable to turn on Convert Gutenberg Data on?