As you know
I fitted 35mm lowering springs on mine a while back and it has dropped it nicely.
But as previously mentioned, When i'm loaded up with gear, I have issues with speed bumps and steep inclines etc. The only bit that catches mind is the back of the CAT, and even that just scrapes.
The other bit that catches is the Bottom of my Witter Towbar, its a bit 3-4 inch deep plate so not surprised that catches really.
Other than that, i love it.
Looks mean too.
Tbh, i would say you wouldn't notice the LOOKS of a 15mm lower chassis much.... but you may FEEL it.
From the post though it sounds as though you'd like to be able to see it.
In which case i would say 35mm like mine might suit more.
It's not massively hard to do, but as also said before, any work you do will screw with your settings, and toe will be adjusted because of the lowering. This is not something you can set yourself along with the camber etc.
good luck tho, i can describe what you need to do in more detail in a PM if you need.