This was also my experience when experimenting with different forks. My theory is that I balance the bike more through countersteering and others balance more by leaning. Less rake:thumb:easier/quicker countersteer. I don't balance by leaning so I don't get any added stability with more rake:(instead we end up wobbley. The way I balance the bike puts little sideload on the wheels, so the wheels that TG hates work fine for us. Whether or not my theory is correct, I have found what works only by trial and error. Anyone want to buy a nice Reynolds fork?
Ed

TG in that long response I think you hit the nail on the head when you said this:

Since most people don't want to admit something is wrong, particularly when they have spent a small fortune in whatever activity they choose to persue, they tend to convince themselves that either its really not that bad or maybe its just them. It is both a blessing and a curse that tandems are not mainstream or cheaper. In one sense there would be so many more of them that situations like this could be avoided. Just image if any tandem shopper could walk into any LBS and get a quick fitting and then honestly compare apples to apples. But alas tis not to be. The good thing is that when you do finally arrive you are unique and a conversation starter and there is a pride in knowing that you are not only doing things for yourself but are also doing it for another human being.

... and remember, I still don't know if it was that particular set of '08 Rolfs or if there was something about all of the '08 Rolfs that seems to throw off handling for us. The '07s that we picked up after selling the '08s have been just fine and neither our Erickson nor the Calfee exhibit the nervous cornering with the '07s that we discovered with the '08s.

This is unfortunately the way it often is with many things. I have yet to make a fork / tandem geometry decision without the counsel of our builders. This kind of gets back to my original set of recommendations to the OP which suggested contacting Santana, one of the other better-known West Coast tandem builders, or just looking forward to picking up a new or new/used tandem fitted with the fork the builder intended.

Again, to drive this point home here's a recent quote from someone who knows something about designing and building tandems: " A frame can't (well... shouldn't) be designed w/o known fork dimensions." That probably extends to even the fork's stiffness nowadays given how different chromoly and even different brands and models of carbon forks can be.

This is absolutely true and that's why I say, the more time you spend at rallies an watching folks on tandems and hearing them talk about their tandems the more you realize that there are a lot of folks who have not found the right tandem... yet. Of course, they'll still offer all kinds of praise for it's handling and what-not but just sitting on their rear wheel for a few minutes will often times reveal that either they're kidding themselves or are masochists.

Again, our Calfee was a love-hate relationship. I was beside myself on the handling thing and even had some discussions with Calfee about beefing up the rear triangle IF a wheel change didn't solve the problem. Thankfully, that's all it was. Weird, but what the heck.

Continuing with this thought, or some thought like this . . .
The difference in the feel of our Wound-Up Speedster has nothing to do with expectations or commitment. I understand about that stuff. No, the Speedster went in the straight line from the first pedal stroke. If anything, I had a higher expectation of the Primera test ride, since I was so primed to love a Co-Mo. From reading this forum and various reviews, it sounded like the right bike for my riding style, which tends to be a bit aggressive and fun-loving.

Which leads me back around to TG's commenting that trail has the opposite effect on a tandem than it does on a single. What if that difference is simply, as justcrankn intimates, that many people are accustomed to steering their single by weight-shift, which doesn't work the same way on a tandem, since the weight you're shifting is a smaller proportion of the total, and a captain weight-shift might impose an unfriendly moment about the frame's long axis.

For my part, much of my two-wheel riding has been on fast, heavy motorbikes, so I bring that countersteering behavior from there, since that's the only way to move one of those around quickly. As I've noted before, when I get back on a single after a lot of tandeming, the bike seems flighty and jumps around, just me overdoing something, possibly the steering. And that was the first thing I noticed about piloting any tandem: don't move those bars so much! Just adjust the statistical average to equal motion in the desired direction. Which is still more bar effort than I use on a single.

So my new conclusion is that it was my moving the bars on the Primera too much that caused my stoker to attempt corrective action, which just excited the bike further. Nothing to do with flex in frame or fork. But maybe something to do with trail.

Further comments, TG?

Only one; this is all that matters: