On the Oade CM R44 vs the 680:
I owned an Oade R44 for awhile and sold it to get the 680. Both are great pieces of gear, but I do find they sound noticeably different. Before I got the 680 when I still had my R44, I did a comp with Chuck and his new 680.
We ran mics (Milabs? Gefell m210s? not remembering now) into my EAA PSP2 preamp. Then PSP2 XLR outs to my Oade R44 and PSP2 1/8" mini out to Chuck's 680 (using an 1/8" > RCA cable, some RCA>XLR adapters, and XLR cables). I doubt the difference in cabling had too much of an effect, and supposedly the XLR and 1/8" outs on the PSP2 share the same signal path.
The Oade R44 recording was definitely tilted towards the warm/smooth/musical side. It sounded very nice, but did not have a huge amount of detail and attack. The 680 recording was much more detailed with more attack, and less warm. On the bright-to-dark scale, the Oade R44 leaned towards the dark side and the 680 leaned towards the bright side (not said in a positive or negative way, meaning I'm not saying too bright in a bad way or too dark in a bad way, just trying to give perspective on one sound vs the other). To my ears the 680 sounds more like a Lunatec V3, and the Oade R44 perhaps more like the apogee sound.
About the same time, Chuck did a comp of AKGs>V3(digi)>680 and AKGs>680 straight in (can't remember the details on his comp -- I think it was two different sets of AKG 460's). The V3 sounds nicer to my ears than the 680 straight, but they have a similar sound. I also listened quite a bit to the 680 vs Oade R44 comp. The Oade sounded great, but I like the type of sound the 680 has better. I also listened quite a bit to the 680 worried that the detail/brightness might be too much and fatiguing over long listening spans. To my ears, it is closer to that edge, but doesn't go too far to be too bright or fatiguing.
I do think that people who like that more classic warm Oade sound may not want the 680. Likewise, people who find a brighter, more detailed sound objectionable may not like the 680. But people who like the V3-type sound will probably favor the 680.
My friend Scott picked up a 680 and got it modded by Busman. One of these days we'll put together a good comp of the Busman 680 vs the stock 680.