Got my comic uploaded to four different platforms (ComicFury, Tapas, Wordpress and, more recently, Webtoons) and... so far, I think more platforms can be really good. They DO require quite a bit of work, however: with Tapas and ComicFury I pretty much upload the same exact page to both platforms and copy-paste the same exact caption, while for WP I need to manually add previous/next page links (I know that there are webcomic layouts available on WP, but I ain't gonna pay $8 a month just to have them, so I'm uploading my pages as regular blog posts, lol). Webtoons requires a different kind of work too, due to the different format and the fact that people on there apparently prefer longer updates, so for now I'm posting complete chapters instead of single pages like on Tapas/CF/WP.
What others have been saying about being able to reach more people is definitely true: most of the people who follow me on CF are not on Tapas and viceversa, and the same goes for Webtoons. It's true that in this way your reader base is more "fragmented", but it's also true that those same people would have probably never even discovered your story if you only posted on one platform
Given that you have an already established novel, however, I would definitely recommend picking a site that allows you to schedule updates, since keeping track of each website can be hard as heck, especially if you choose to post updates on different days! D: