There have been lots of opinions published on all kinds of sites, from respected to new-to-the-game. And thats just it - it's someone's opinion - based on reading someone elses or by seeing a site "move up" when they did something and somehow attributing the last action they took to be the cause. It's really hard to attribute just one action/cause to a raise in visibility.
I don't believe that server location is critical to SEO. Google are a globalised company. They have off-shore facilities. I think that having to host in the country you're targeting has its roots in a sort of protectionism approach to service provision - almost European in its idea (look at the policies adopted by Ireland, France and Italy with regard to sale of the .IE, .FR and .IT for example).
We have sites hosted in Ireland that target the UK and EU and US and sites hosted in the UK and US that target Ireland and we've never had a problem.
Before anyone rushes out with the page load "trump" card - from Google's perspective - a lot of sites running in China, India, former Soviet countries, and Africa - these are SLOW sites. These are bedroom-run servers with dial-up connections - most sites running in Ireland, even if badly written, aren't going to fall foul of this new initiative by Google.
Also, Googlebot doesn't run from every country, therefore measuring the latency from Germany to the US doesn't indicate Germany - to - Ireland performance issues.
@OP many factors - such as your choice of domain name, languages used, inbound link GL's, words used and other signals affect where you end up placed, including CTR (always ignored yet a key foundation stone of "what makes Google different" when it first launched).
If you see higher ranking in Google.com - are you really at Google.com or an Irish version of Google.com? Add &gl=us to see US type results (again close but not exactly how they might be seen from Texas or NY for example). The only way to get to Google.com in Ireland is to go to Google.com/ncr.
hoep that helps!
