Thank you all for the very informative and helpful replies.
I went to a local dealer (RAF in Amsterdam) and had a very through listening with a variety of my music.
Here are my impressions, all these were hooked up to a Marantz 4002 amp:
The IQ5 SE's are absolutely amazing, both for their size and especially for their price. They create an an amazing soundstage and they never seemd to miss a beat, except when I really pushed them to mental levels with an aria from Renee Fleming's Alcina, at the hight of the vocals I have heard some clipping. But apart from them, they took Patricia Barber and Dave Mathews Band like ducks to water.
The 685's, compared to the Kef's sounded more accurate, precise and, for the lack of a better word, gentle. Their clarity was definitely a step up over the Kef but they could't create the whole enveloping staging, I'm guessing for the lack of sheer size. (They, too clipped at the same volume at the same place with Alcina by the way, but I have to re-emphasize, I was really pushing it)
Then I moved over to the IQ7 Se, well, they certainly give more substance and more space to the sound but they also take away some of the focus and precision of the 5's. I remember reading a similar comment on the review and I absolutely agree. So, I pretty much eliminated them. I figured, If I were going to blow the budget, I'd blow it throughly and go for a real step-up.
Then I figured, with the stands, the 685 would cost me almost the same as the 684s, which are my fetish speakers for years, so I gave them a blast. Well, I was simply in love. They combine the immersion of the Kef with the accuracy and clarity of the 685. But then, they are 500eur per piece.
While thinking about how I can manage to afford the B&W's, I did some more comparisons between the IQ5s and the 684s and to my surprise, the little Kef's held their honor very much intact.
So, if I had the budget, I'd certainly go for the 684's, if only for their presence, but value-for-money, I think the IQ5 SE's are quite unbeatable. (200 eur!)
If the price difference were a bit less, I would, again, go for the 684. But a pair of the Kef, less than a single B&W...Well, the 684s were fantastic, but not THAT fantastic.
But that won't mean I will stop lusting over the B&W's. I'll just lust over them while listening to my fantastic little Kefs. =)
Hope this was helpful.
Thank you again for your assistance and happy listening to everyone.