I wouldn't be so quick to slam Felder for not wanting to take the machine back at a higher price than what they paid for it the first time. They've already paid the salesperson. They've done all the work on their end. I would not think it would be reasonable to expect them to do it all over again and have to sell it at no profit. Their suggestion is the best solution. He will get more for it selling it direct to an end user.
I'd also second the idea of looking into a separate saw/shaper. Doesn't the B3 have tilting spindle on the shaper, as well?
The full combo is nice, but there are definite downsides to the 4-function. For instance, if you're sawing something with a long off-cut on the right of the blade, you have to be set in jointer mode and swing the jointer guard out of the way. It's a bit of a pain if you were set up to plane. Also, if you had the fence on the jointer, you have to take it off.
Unless you really don't have the space, or the cost of the full combo is much less, I think the saw/shaper and j/p (as "separate" 2-function machines) are better.
I agree with separates too. Many times separates can save more space if you are rolling the machines around a little bit. A combo pretty much has to sit in the center of the room or at least have enough space on both sides for working. I have my J/P against one wall, and the S/S near another. The common space between them is my work space. Maybe you have looked at your layouts and proven it is more space efficient in your case, but if not, you can find sketchup models or simple CAD files of many of the hammer machines to compare which is more efficient for your shop.
From a functionality point of view separates are nicer. Maybe you are more organized than I am, but I cannot wait for the day until I have enough space for all my machines to be single use.
Cost wise, the combo unit is more cost effective, but I tend to think that ship has sailed now that you have taken delivery. $6k will not fly for most.