I think it depends not just on whether you shoot landscapes, but also on what format you shoot, how much resolution you have, and your compositional style.
I have all three of the T/S lenses (the original 85mm PC though, not the updated PC-E). I started out using them on DX format (D300). 99% of the time if I was using shift it was for flat-stitching, which gave me a quick and easy way to boost resolution (20-28mp depending on final crop) for the times when I didn't want to shoot and stitch a rotational pano. For this use, the default configuration is beneficial, because you can use horizontal shift for stitching, and still have the option of using tilt to control the plane of focus. If you switch the orientation, you won't be able to use tilt when stitching. I also found that since 24mm is not all that wide on DX format, my compositions rarely needed any perspective correction; you're shooting from farther back than you would on FX, and as a result it's easier to have the camera level or close to level. So I rarely needed shift for perspective correction; it was pretty much just for stitching, which made the default configuration preferable.
Now that I'm shooting FX with the D3x, things have changed a bit. The 24 PC-E is a true wide-angle, so filling the frame means getting much closer to the foreground subject. As a result, shift is more frequently needed to control perspective, and I can see how having tilt and shift on the same axis would be beneficial for this lens. Additionally, with the larger format I find the 24 PC-E less attractive for flat stitching. For one thing, I now get 24mp without stitching. Plus, image quality degrades noticeably at the edges of the image circle on the 24 PC-E (more so than the other two in my experience), and doesn't really do the D3x sensor justice. So if I were going to stitch for extra resolution at this focal length, I would rather shoot a rotational pano.
The 45 and 85 PC-E are still useful for flat stitching on FX, especially when I want 5:4 or square compositions without having to heavily crop a 3:2 image frame. The 85 in particular is spectacular all the way to the edge of the image circle. And with the longer focal lengths, perspective control is less of an issue (especially with the 85).
So my suggestion would be to keep the lenses as-is if you're shooting DX, especially if you want to do any flat stitching. Spend some time shooting with them and see if you ever find the default configuration to be an issue. If you're shooting full-frame, I think the 24 PC-E is more useful with tilt and shift on the same axis, but with the other two I think they're fine as-is.
