I can't do a direct comparison, not that familiar in detail with the 500L, so I can't do a direct comparison, but I hope this helps.
Not had any issues with my 500x in almost two years.
The boot is not that big on the 500x, smaller than the Tipo we had before
No one has complained about lack of passenger space, which is fine for us as we usually carry no more than 4 adults up to 6 feet tall.
The boot is not a problem for our holiday luggage for the two of us, but we do have to let the seats down for our two large suitcases.
I think its a well built car, no rattles or anything, still looks as good as new!
If a 500x suits your requirements, you need to have a serious look at one and a test drive