Do you think it's worth upgrading to 1.5 if you have 1.0.15 with quite a lot of mods, components and plugins that work for it? Is there an easy way to do this?
If you are considering an upgrade, I would test it thoroughly first. On paper, list all the mods, components and stuff you use on 1.0 and then add the 1.5 counterparts. After that is all done, get an installation up and see how well it works. If your site now is working fine and you are happy with it... what is the point in upgrading?