No impact. As long as you keep the URL intact. If you're using the .htaccess and mod rewrite, don't ever change it.
Changing hosts doesn't affect SERPS, but the location of the servers can. You can use the DP geotargeting tool to check the location of the server.
i dont think that will affect your site but u have to take care that your site must not go down during changing the name server and this procedure.other wise there is a chances of lost ranking if your site wil be down.
Do you think the location of server has serious influence on rankings? I mean like: server in USA and site for one of European countries.
Try to make the chang as quick as possible, so if the site does go down, it only goes down for a small amount of time. Can I ask why you are changing hosts?
Geotargeting Website To Country Tool What is this good for? Maybe you want to know where your servers are physically located with your hosting company. Also, some search engines (such as Google) have the ability to filter search results based on their physical location (geotargeting). This could be used to determine why your site is showing in a certain country. http://www.digitalpoint.com/tools/website-country/
Thanks a lot. What about the tld extension. I have site for Poland but my site www.ittechnology.us has us extension. Is is going to have serious impact on rankings?