This thread has run for over a year, so it's time to ask Reinier to answer his own question. Has it stopped, and where?
The swarovski scope ATC 17-40x56.
Having just one: NL 10x32
Having two: NL 10x32 + SLC 8x42
Having three: NL 10x32 + SLC 8x42 + Curio 7x21
Having four: add the EL 12x50
All 4 powers and all needs (for me) covered.
And of course a scope. No need for a bigger one.
This (my quote) actually is the answer to that question. This is also my line up at the moment: CL 7x21, SLC 8x42, NL 10x32 and EL 12x50. Together with the scope ATC 17-40x56. I also have the trinovid 8x20, but I think I will sell it because I have the CL 7x21 now.
My first thought was: one pair of binoculars for bird watching and one pair of binoculars for low light situations. So NL 10x32 for bird wathing, since I do that pretty much only in daylight and I prefer 10x. This pair of binoculars has to be as light and comfortable as possible. I think a 10x32 is great for that purpose. The SLC 8x42 has an exit pupil of 5.25mm, so suited for dark woods and twilight/night.
I could have gone the other way around: 8x32 and 10x42, but then both woulde have an exit pupil of around 4mm and I would miss a pair with >5mm exit pupil. And in broad daylight I do not need an exit pupil of > 3.2mm. It's the weight that counts, when doing some hiking.
However, I am a 10x person and was curious how an EL 10x50 performs and found a good deal. I compared it with my SLC 8x42 and found that the SLC 8x42 was actually a bit brighter in dim light (although the NL's and EL's have a bit more spark in broad daylight, the SLC are just a bit brighter/more contrasty in dim light imo.) So I didn't see a lot of purpose for the EL 10x50 and found a good deal for an EL 12x50 as well. I decided to keep the EL 12x50, because I can hold it steady enough and really like the extra magnification. This is the bin I take with me when I do some serious birding and weight isn't really important. It's also really usefull for watching wildlife in open fields at dawn/twilight. (An SLC 10x56 would have been a contender as well, but the EL 50 is quite compact and lighter compared to the SLC 56.)
I like to have a pocket bin as well. Just to put in my pocket when I am wearing a jacket or hang on my neck without even noticing it a lot, when I am outside with my kids for instance.
So now I think, two pairs of binoculars is just one pair short. Three is sufficient in my case. If I would be an 8x person, two would be sufficient: a pocket bin and an 8x32 or lightweight 8x42. Being a 10x person, a pocket bin (in my case 7x21) an 10x32 and an 8x42 (or 10x50) is all I need.
The EL 12x50 is purely a luxury. Having four swaro's is a luxury as well, I know. It's not only about bird and nature watching, I became an optics snob as well. I am a swaro fan boy too. I actually didn't give Leica and Zeiss a lot of chance. The way a swarovski looks like (I like the green colour), the way it feels, the eyecups, the accesoiries, I pretty much like everything about them.
So yes, I am very happy with what I have now! I still feel some attraction to the Habichts, but that can wait. I do not see a lot of purpose for them in my line up.