I have no idea if this will be helpful or not but HERE HAVE SOME PICS, maybe this will give an idea of scale???
Honestly, I think it's all about what impression you want your book to have! Here's two of mine -- in the interest of full disclosure, the Today Nothing Happened book (manga size) I'm holding was printed at Ka-blam, before I switched to Whitlock Printing, but while the Runewriters book is pretty close in size to the Ka-blam standard format comics, I've never printed at that size through Ka-blam, so I can't speak to that product.
Both books are perfect-bound (which I'd advise doing if you do buy from Ka-blam, from what I've seen, the quality jump from saddle-stitch to perfect-bound is noticeable!)
The manga-style feels more like a little digest; whether that's a volume of manga or an Archie Comics digest, so I felt like it'd be a good fit for my silly autobio cartoons.
Runewriters I've always imagined feeling like A Comic Book, so I went with the standard western size.
Detail is only one piece of the puzzle, I think -- like, you can put a lot more detail into a small 3-panel page than a big 9-panel page. But if you want a lot of high-detail shots in the digest-sized book, I think you'd likely need to be working with manga-like pacing -- more often using 3-5 panel pages, taking time for establishing shots, etc. If you (like me) want to cram A Lot Of Things Going On in every page, that's going to be harder to do in high detail with a digest-sized book.
The thing is, you probably won't be printing manga or mainstream comics. You'll automatically be printing an independent webcomic, regardless of the art style you use, and those don't really have expectations attached. So unless you have a specific audience in mind who'll favour a specific size, I think the choice is what kind of book you want to imagine your work in!
At least, that's my take. : )