One advantage to using the Rollei for panos is that you can crop the pano out of the middle, bottom, top, or indeed from anywhere in the vertical extent of the 6x6 neg. In this way, when shooting, you can effectively have front rise and fall. You can know you'll later crop out excessive sky or nearby pavement or whatever.
Or you can as easily make vertical-orientation panos without rotating the camera, and choose to crop that vertical segment from left, middle, or right portions of the neg for effectively front shift effects.
And of course it's much cheaper than buying an XPan and lenses... but in practice it's cheaper only if you will actually find it convenient to carry and use.
Would you go out deliberately looking for pano shots? Shift your mental gears so that that is what you will mainly see? Or do you think pano opportunities will appear unexpectedly as you're shooting "normal" proportioned scenes? Do you resist cropping pano proportions from a 35mm neg? Do you carry your Rollei often?
I've given some thought to an XPan too. But I'm not so sure I'd want to dedicate myself that intensely to panoramas, even though there is the 24x36 option too... which seems like cropping to 35 from medium format. And its lenses are few and slow. I often carry a RF645 (also limited to a few f/4 lenses) or P6x7 camera (with several f/2.8 lenses), and so far I've been content to crop these MF negs to whatever proportions the image seems to "like". And if I avoid or minimize some building's keystoning by including excessive foreground, I know I'll crop that out later. There's a lot of flexibility in medium format.
But that 30mm lens for the XPan is its wild card, something I cannot duplicate in my medium format rigs, and maybe you can't with the Rollei either. If the 30mm, even considering the center-grad filter, is a big draw for you, then that settles it!
