I've been running the FF200 lights for about eight years. Just put a replacement set on a year ago, the reflectors had degraded. We did a little experiment at a get together near Barber last year. I had a 55w HID light at the time. We fired up the Hellas while covering the HID, then uncovered the HID, there was no improvement over the Hellas, not brighter at all. The HID later failed, I went back to a standard H4. I don't like losing all lighting in a failure.
As my morning commute is in the dark, on back roads, I do want my lights to be functional, the FF200s are. They also utilize the single ball mount. I have them mounted on my tipover bars, with no issues with jiggling or bulb life.
To answer your question on FF50 vs FF200, the 200 put out immensely more light. Hard to measure. I run these on high beam only, kicked in by a relay, and a switch to kill them if I want. The same relay feeds a set of fog lights on low beam.
Another option, go with a high output H4 bulb, say maybe 80/100 watt. Bypassing the standard harness, and installation of a Bakelite headlight connector will be mandatory if you do. The extra current will kill the Jbox, and the extra heat will melt the headlight connector. Murphs' has a plug and play bypass that also has a provision for driving lights.
Just about anything you do will help the anemic stock headlight situation.
Have fun.