600LT isn't that much special than a 570S with a tune. It has three things that make it or break it. The exhaust placement (which has a huge risk for fire). The MSO roof scoop, which let's be honest makes the looks of the car and is a rare ridiculously expensive option. Same with those Senna seats. Driving wise you would get a similar experience with a 570S (which has some insane deals atm) with an aftermarket spoiler and exhaust.
The only competitor to the 600LT I see is the Performante which in truth is the better car overall. It has a more advanced aero system, it handles better, it is faster, it sounds way better and looks in my opinion a lot better than the 600LT. The only thing that comes to mind that 600LT has over the Performante is practicality.
These are my thoughts, from the short experience with both cars. And yes, beware of that McLaren depreciation.