Hi Polska,
I currently own both 2003 and 2005 FE650s and in my opinion the later is a far superior bike. I've had the 03 SEM stator rewound by Sparks, a forum member and with the valves set, it kicks first go. Starter is useless, forget about estart unless you do a lot of mods. Plenty of info on here about that. 03 has Dellorto carb, it's ok but it's no Keihin. Later cases look a quite a bit stronger to me. I have both my motors on the bench side by side atm. Spherical rollers seem like a good idea, however unless you know someone well with a machine shop for the boring of the cases (where the mains would sit) and sleeve to house them, it would be an expensive option. Again, have a look at bushmechanics write ups. He's done a lot in this area and it is highly credible info imo. Others also contribute well in these threads it must be said.....The 700 in this earlier version likely would expose the weaknesses. If it's not revved hard, it may just last?
Having said all this, my 03 has been fine. Owned it since 2006. It's had its problems but once sorted out a bit, it's churned up many a proper roost. But keep looking for the later version. Most would be much happier with 05 on.
Regards
Damo