Not wishing to step into a minefield, but that swingarm dorsal fin doesn't look to add much in the way of stiffness/rigidity/strength. Did anyone do any analysis of that mod or was it more of a "let's add a chunk of steel and hope for the best" approach or should I say empirical engineering?
And while I'm here, why do you want to lower the bike? Lowering teh center of gravity gets hard parts closer to the road and as an added disadvantage also requires greater lean angle to go around a given corner, so more lean and more stuff close to the ground, isn't usually a good combo for a motorcycle. That could be an optical illusion of course. Many CX's are modified to have what appear to be very high seats, but I have never seen one being ridden to see how high they really are.
Or is it just to compensate for that really high looking seat? If that's the issue, perhaps lower the seat and tank a few inches instead of dropping the whole bike.