Hello Basel,
it can be pretty overwhelming trying to make this decision, i know !
seeing one in person can definitely help. if there is no way to see one in a store, you can check this
thread, maybe there is someone living near you who could meet you for a coffee and give you a demo. you can leave a message requesting a meeting in your city.
as for format conversion, you are in luck ! .lit format is one of the easiest and best to convert, because it modifies very little the core html code so it should give good results when converted (retaining formatting, etc.). if the files are drm you will need to google something called ConvertLit (our forum policy prevents us from explaining precisely how to break drm...). if they are not drm, they can easily be converted using
calibre for example. calibre is a free library management / conversion tool made by forum member kovid goyal, and if you get a sony i think you'll find it invaluable.
good luck with your decision ! let us know how it goes.