I don't own the Eheim and therefore shouldn't post but two things come to mind:
1. The XP3 is not unacceptably loud, in fact I don't notice it whatsoever. I wouldn't consider noise a problem.
2. Build quality meets my expectations and is superior to the products I've previously run into. I've not used Eheim before as they're generally $300+ for a decent sized filter in Canada.
3. The XP3 plugs almost instantly in my tank. To be honest it drives me asbolutely raving mad...I can't really communicate it here. But within 48 hours the things slows down to a crawl nowhere near adequate for a 125 gallon.