Hi Bill, I'm pretty familiar with the Jensens and you have described them accurately...they are a "feel good" cap that will make most systems lean to the 'pleasant' side of real. They are very seductive in that regard and even in a generally well balanced [referring to tonal character] system they are difficult to remove once you are accustomed to their sound. I would also recommend them to anyone with a slightly "hot" or "etched" system...perhaps someone with NO tubes anywhere through the signal path and that might lean to a traditional ss sound...these will be ideal.
As for the Duelund cast caps, not only are they more resolving (a good thing) they are also less warm (but still a GOOD thing) because what they REALLY are is utterly natural and realistic sounding.
In my experience I have heard the Lampi L4G4 with Jensens in my system and instantly heard its obvious appeal. Once I almost immediately caught the Lampizator Dac bug I decided to move up and everything I read and heard about the "Big 6" convinced me it was a perfect choice, so I ordered one. As it turned out due to a temporary backlog of Duelunds, I went with the VH V-caps in it and learned about their particular character too. Can you say: Detail, transparency, dynamics...did I mention Detail? They were quite a contrast to the Jensens and I'm sure that in a more 'traditional' and perhaps tube-rich system they would be welcomed with their strengths. But the Duelunds finally arrived and went right in.
Here is what I'll say about the Duelunds (and please remember both my TRL Dude AND TRL GT-200 monos are fitted with them too); "Reality has landed..." Take whatever you liked about the Jensens, whatever I liked about the V-caps, whatever anyone may find as a positive attribute about any of their favorites and distill them all into a perfect blend. What you'll get is what REAL sounds like. That's what they sound like. Real. No excess... no 'lean towards...' No distinguishing flavor... Just real, honest, truthful, natural music as if it was there...or, I should say: as if it was "Here, in your own room".
IMHO do not hesitate to go with the Duelund cast copper caps wherever you can. (Yes, fortunately / unfortunately, whichever way you vs your wallet may see it), their effect IS cumulative with each piece of gear in the food chain.
Remind yourself how seriously better some piece of new equipment really made you feel? I mean a real, significant and obvious advancement in bringing you 'closer to the real thing'..in YOUR own room?
Do the Duelund(s). You'll feel it again.
My personal two cents. Keep in mind they do need quite a few hours before sounding their best but still sound darn good with barely a hundred. Be patient on up to 400 or more before they're finally at their best and don't be too surprised when a few months go by and you still note subtle aspects of better-than-ever...
Good luck with it and Happy Lissn'n!