I don't mind sideloading either. But I know that most people just won't do it. I just use calibre as my main library and slide load as needed. While I use nook and most of it is delivered wirelessly, other locations are not. Libraries that use overdrive for example and that requires sideloading. Well for most e-ink devices, overdrive does have a tablet app. I also like having calibre as my "backup" system. I have been burned too many times with ebook stores closing and I lost out on books that I did purchase.
Regarding scribd, it is a good company however I didn't like their tablet app either. I couldn't get it to work with audio books (at least with my android tablet anyway, and the feedback option in the app always crashed lol). Normal book reading was fine though. I did read a few books on scribd I didn't have access to in libraries , but I also let my subscription lapse. I just have too many in my purchased "to read" pile to justify continuing the subscription right now.
Oh btw Bear, you might want to take a look at calibre. You can easily convert and copy a book to your device in one go if you need. It does a nice job of converting epub to mobi (kindle) and vice versa. Among many other formats. Of course, perhaps, this is what you already do.