MY GOD those 20" are HUGE! I don't think I can drive anywhere in those since I accelerate fast and brake hard. Plus, I would imagine the ride would be very hard.
I think the 19's are great looking but when it comes to value and comfort, the 18s are the way to go. Thats the only reason I downgraded my 19s to 18s Brabus Mono VI. I still miss those 19s and those wide lips.
Oh yeah, to answer your question, based on what I think..and considering I've never seen a real W210 with 20" on before but looking at your picture..It seems like it would look lower since you're increasing the size of the rim and somehow the space between the tire and the bottom of the wheel well looks less. Maybe its a angle situation but thats what I think.