Just installed iSilo (the ebook reader I used to use on my old Palm Vx) in GarnetVM. Suprisingly iSilos Autoscroll feature is working just fine on my N800. No tearing.

Autoscrolling is almost as smooth as on my Palm Vx. If even Garnet VM can do this - and I guess the main focus in Garnet VM development isn't exacty on smotth scrolling - it can't be that difficutl for an ebook reader running natively on Maemo.