I have owned the M 40, 40 Limited, and 40 XS. I sold the Limited, and happily kept the other two. I keep the M 40 on the MX or ME Super, and the 40 XS on the Super Program and K-1. Both are great little lenses.
Originally posted by Matt_Dodwell_UK Which are Pentax's decent film SLR's with AF and in camera aperture controls?
The question of which film bodies can control aperture gets asked quite often, so I put together this list in another discussion:
aperture controlling bodies? - Page 3 - PentaxForums.com
Edit: there are some plasticky film bodies I'm personally not a fan of, but they may serve you well. Generally, the good film cameras with full aperture control would include the Z-1/PZ-1, the Z-1p/PZ-1p, the MZ-6/MZ-L/ZX-L, and the *ist. These are all auto-focus and offer direct aperture control. The manual-focus Super Program has aperture linkage, but doesn't offer direct control. This means you have shutter-priority shooting and the camera sets the aperture for a correct exposure.