Surprisingly, the Seeker 2 Pro isn't that much heavier than the other Olight bike lights that I have. I just weighed all 3 lights:
Seeker 2 Pro - 6.9 oz
BFL 1800 - 5.8 oz
RN 1500 - 5.7 oz
The diameter of the Seeker 2 Pro is the same as the BFL 1800, but obviously as shown below the Seeker is much longer. In turbo mode, the Seeker 2 Pro is the brightest light out of all 3, but that only lasts for about a minute before it steps down to 600-ish lumens, which then isn't as bright as the BFL or RN lights at their high modes.
Side by side, the RN 1500 and BFL 1800 lights have approx the same brightness & output. The BFL has a slightly brighter hotspot and more of a neutral/cool white color (very white looking), and the RN has a slightly wider spill with a more neutral/natural white color (more yellowish looking). Riding on the trails you wouldn't really notice a difference but it's pretty obvious when they're side by side.