As Smit says, the retention on giganews is rather good at 90 days, but you pay a premium for it. The 70 days you'd get with newshosting would likely be more than sufficient. Not sure on this myself, but do newshosting have servers in Europe? I've always gotten very good speeds with giganews.
As for newsleecher, I much prefer the interface to grabit although they both get the job done. 30 day trial on newsleecher too, so no reason not to test it out before deciding. Not worth paying extra for the supersearch service though, theres plenty of free nzb sites out there to use instead.