Thank you for your answers. I haven't found any issues with spacing when forcing left alignment yet, which I have always done because I believe that this is optimal for reading quickly, along with no hyphenation.
I only recently discovered that patch which allows for optimised text rendering, and I love what a difference it makes. I use Literata, which I find to be a very pleasant font, and particularly appreciate the non-slanted italic variant. The difference with kerning enabled is very obvious with words such as "York" or "Written".
I would be prepared to experiment with the epub format if there were further typographical benefits to using it within the parameters I've stated: left alignment and disabled hyphenation. I have not yet accumulated sufficient experience with the optimised legibility setting enabled by geek1011's fantastic patch system to be aware of what those might be though.
I must reiterate, I really appreciate how great this forum and community is as a resource for learning how to optimise my device. If not for this thread I wouldn't have investigated a mechanism for enabling kerning for Literata in kepubs. I feel like I just got another free device upgrade
