Lord, I hated the Manfrotto QR system.
Hejnarphoto is run by a good guy in the Chicago suburbs, and he will email back if you need help. The Arca-Swiss conversion kit made me love the 410. Note, there are two A-S conversion kits, the original design and a later one that puts the camera sensor over the horizontal pan axis (easier to have all your movement axes converging on the sensor axis). The later design is a little better for panoramic use. I have his original design and may replace the top plate with the new design. Hejnar stuff is simple and modular, and exact dimensions (and CAD diagram) are given, so you can use any clamp style he has or see if you can use another brand clamp you already have.
If you have an idea for a specialty 6061T aluminum product not available elsewhere and just want to get it fabricated, he has been known to run up a prototype if he likes the idea enough to make it part of his product line, and sell it to you at a reasonable price provided you give him feedback on the prototype.
