I said I'd check it out further, and I have. Now there is NO DOUBT in my mind that recording at 96kHz is a big deal for anything generated electronically inside the computer. For signals coming in from the outside, the input filters and converters pretty much keep things under control. But amp sims, virtual instruments, etc. can easily generate signals that go above the clock, and fold back into the audio range.
 
I created MIDI sequences for Addictive Drums and a the Z3TA+ "Melody Maker" patch. For the latter, I played block chords and transposed a copy up an octave so there would be plenty of high frequencies. I then ran the MIDI sequences at 44.1 and rendered, closed, opened Sonar at 96k, opened the same patches, ran the MIDI sequences, and rendered the resulting audio to 96k.
 
I then opened up the original 44.1kHz project and imported the 96kHz files. But wait, you say...don't you lose the 96kHz goodness because you're bringing them back into 44.1?
 
NO!!
 
That's what blows my mind. The difference with AD was subtle, but noticeable. The cymbals were less harsh and more melodic, and the attack on the drums seemed more natural. But the difference with Z3TA+ was startling. It wasn't subtle, it wasn't something where you had to switch back and forth and listen really carefully on headphones...it was the kind of difference where if you can't hear the difference, you need to pursue a career that doesn't involve audio. There were high frequencies that simply weren't there at 44.1, because they were reproduced instead of turned into aliasing.
 
As far as I can tell, this has nothing to do with 96kHz having an extended response as much as it is being able to reproduce sound cleanly within our usual audio range. When the harmonics fold back from hitting the clock, they fold back out of the audio range. As 44.1 can reproduce sound within the audio range, it was able to reproduce what was captured at 96kHz.
 
That settles it. I'm going to start recording at 96/24 starting now, and see what I can get away with in terms of track count and latency. If I can record at that sample rate, it's worth it. The fact that the advantages survive even when brought back to 44.1kHz is the icing on the...cake.

Thanks Craig.

It's info and ideas like this that make me so highly value the forum.

I'm definitely going to start trying this to see how it works.

Oh. and the self-serving part: I will be doing a presentation on this as part of a panel at the New Music Seminar in New York on June 10. I originally joined the panel to be the voice of reason about why I didn't think it was worth going with 96kHz, so I did some research to collect real-world examples that would justify my position. Instead, I found out my position was wrong.
 
The key point here is I think there are two separate issues - recording at 96, and playback at 96. I'm still not convinced 96kHz is necessary as a consumer playback medium, but for recording electronic instruments and processors, I just became a convert. I better get another hard drive...

Anderton
...I'm still not convinced 96kHz is necessary as a consumer playback medium, but for recording electronic instruments and processors...

While the difference between two pieces of audio rendered at 48kHz and 96kHz might not be evident, I can believe that there could be a big difference for two 96kHz audio signals added together then exported to 48kHz compared with the same two 96kHz signals converted to 48kHz before summing.  For this reason I think that working at 96kHz would be beneficial, although I have never really tried it.

But I am concerned that there might be some particular softsynths or effects that don't work properly at 96kHz.

Interesting,  
I record at 88.2k as rendering the files is divisible by half and supposedly less prone to downsample rendering errors. Where 96k is a non integer sample rate.
 
It could be considered the conversion algorithms in DAWs are much better nowadays and it is not an issue.
 
So apart from not much less HDD space is there any benefit going to 96k?
Or rather a better question does 88.2 give a similar result?
 

What an eye/ear opener! I shall put this to the test :-)
 

It's the maths ;-)

Thanks again, Craig. 
Another great post by you.  I have just added the Octa Capture to my setup and was going to do some tracks along the same line.
 Your posts are always so timely.

Bjn, some folks here do video and hence 96 since the video distributed at 48 often. IMHO, no reason to use 88.2 over 96 other than disk space and processor consumption.

BJN
Interesting,  
I record at 88.2k as rendering the files is divisible by half and supposedly less prone to downsample rendering errors. Where 96k is a non integer sample rate.
 
It could be considered the conversion algorithms in DAWs are much better nowadays and it is not an issue.

 
Yes, you nailed it. Sample rate converters that use 64-bit calculations have more than enough precision to get the job done. 20 years ago, I would have given you a different answer...
 

So apart from not much less HDD space is there any benefit going to 96k?
Or rather a better question does 88.2 give a similar result?

 
88.2 will give similar results. However, it seems there's motion toward making 96 the standard. I could see a time where downsampling to 44.1 won't be a factor because 44.1 will no longer be that common.