Yes, I think the 60XL paired with a 90mm and 40mm would be a great three lens kit. I have the 90 HR-W and 55 APO-SD, and depending on how the 55mm performs on the Credo 60 I might just add the 70HR and 40HR to fill the gaps instead of get the 60XL. I'm sure the 60 is better, especially off center with movements that the 55mm, but I'm interested to see or hear how much better. The 55mm has a massive IC, but will it be up to snuff? The 40HR is the only lens I'm truely resolved to get, but the 70HR is looking very attractive if the 55mm performs well enough, and I'd save a bit of cash.
I have both the 70hr and the 60xl. The 60 is just so versatile with the wonderfully large and sharp image circle. I agree that as a single focal length the 70/72 is a better choice. I recently picked up a used TC and the 70 sits on that all the time.
Honestly I would leave the 40hr behind before I ditch the 60xl. I think it is a perfect match with the 90mm focal length.
Dave
Dave