I'm a bit late to this discussion, but I started sending out queries for my 225k word epic fantasy a few weeks ago, so thought I'd contribute my experience thus far.
I did a lot of research on which agents I thought would be a match for my book, then picked out four - two from the US, two from the UK. The US agencies accepted query letters only, and they quickly came back with rejections. One was a form letter, the other stated that the book
did sound interesting, but the word count was simply too high for them to consider it. Both these agencies have strong rosters of epic fantasy authors, but many of those seem to have signed
after they'd had their first novel published.
One agency in the UK (Zeno) asked for a partial after I queried them, but with a strong caveat in their response - they basically said to be aware that manuscripts of that size were all but impossible to sell from first-time authors, and that the standard was around 100k. So they were giving me fair warning to expect a rejection, but at least leaving the door open in case my writing absolutely blew them away.
The other UK agent I submitted to was John Jarrold, who asks for a sample straight up. Based on what I've read, I'm confident that if he sends me a rejection, it will be for reasons other than the word count.
So: my general, admittedly still very limited, experience backs up what I've read elsewhere - that if you have a well-edited manuscript that still has a high word count, a) you're going to need to be
damn good to get an agent, but it's possible, and b) aim to submit to the UK first. It's not that length isn't an issue for UK agents too, but they seem more willing to have a look at your writing before saying no - I think that's why many UK agencies ask for sample pages on the first submission, whereas few of the US agencies do. My impression that if a US agent sees your word count is higher than x, it's an automatic rejection before they ever look at your work.
Having said all that... I'm still pretty new to all this, so I'm hardly an authority on the matter. Anyone with a conflicting experience, please feel free to disagree!