I wouldn't recommend letting the download manager update your poser with a new service pack, unless they change how it behaves. It replaces all of your customizations, including those for EZSkin (and probably others). It's kind of annoying. 

Also, if you find it crashing after it tries to verify your S/N, it's probably because the number was invalid. When I copied mine, apparently I had not copied one of the characters and it kept crashing. It wasn't until I went to the website and it complained about the S/N being invalid that I realized that I hadn't correctly copied the number over. 

Anyway, in case you are ready to update, I thought you might like to be warned of these little details. I haven't really had a chance to really try out the new SP. Hopefully it fixed the issues with M4 and super-conforming clothing.