IMO 550 is a better car. And judging by prices for comparable mileage/condition cars, price would reflect my opinion.
575 are now worth less than 550.
My opinion is based on personal experience of many cars now... maybe 15 different 550,s and half a dozen different 575's.
A 550 is more of a drivers experience, the cable operated throttle being the most important aspect. 550 has a tighter ride but 575 have the US market targeted soft roly poly suspension/shocks, and the F1 shift really is a bit crap at urban speeds. Fine over 80km/h though, really it is.
550 have nicer cockpit environment IMO, but both are not perfect FWIW.
Stick shift is important... they are so flexible. You can pull away from 0 in 3rd gear without using any throttle at all, and silentyl glide to stupid speeds... stealth like... I drive in 3rd and 5th only in 550 when just getting about. For hill start you need 2nd. Trying to use all 6 gears makes for slow progress unless actually going hard in all the gears. You CAN get 575 with stick shift though, just not ozzie cars. But the fly by wire throttle and soft shocks spoil it still, IMO.
I wouldn't have a 575 at any price, but I'm actively looking for a 550, of a certain type....
550's are holding up better over time with collectability, thery simply made too many 575.
I noticed this thread and FF's response, thought I would give a real world opinion from an owner (and a new poster ). A little background first. Graduated from Uni in 1972 and wanted to make enough money to buy a Ferrari. Passed on a Daytona @ 3,700GBP and a 250GTO at 9,100 in London in early 1975. Back to Oz and settled in Canberra for 30 years. Owned various cars over the years including 2 F's which I loved, one I kept for 17 years. I retired a few years back and on the bucket list was a few cars, including my absolute favourite a 330 or 365 GTC. Decided to keep only for a year or two or three and have been fortunate in my selection. My latest is a 2002, 575 which was a spur of the moment as the price was too good (in the middle of the financial crisis). I too have driven a few 550's and a couple of 575's.
In England the roads are so crowded now that many 'exotic' car owners go over to Northern France for their 'high speed' runs. Over a few years I have met several whilst touring the WW1 Battlefields. I saw many excellent modern cars, including 550s and 575s, and of course managed to pull a few rides and drives.
Buying a really modern Ferrari and not wanting the 'latest' tricks, even for me at >60yo seemed a bit silly, so I had no objection to a paddle shift. In the real world, driving on Australia's 'less than perfect' roads means the suspension need not be too hard. The 308 QV I had was eventually set up for the track, and driving to the QLD Rally in '91(?) was an absolute PIA. So back to normal.
Driving in SE NSW I have found the shocker ECU upgrade (from #183960 to #201673) has restored the car slightly firmer handling that I prefer. The stick shift on the 550 is a usual stick shift, however the car has SOOOO much power the paddle shift is perfect. When I bought the car in Mosman, I can tell you getting the car to the edge of the city was VERY nerve wracking, it stayed in AUTO until then.
As I said in the real world the V12's are true GT cars. Of course there are so many similar cars (Aston's, Maseratis etc) in 2011, but after 40 years of driving Ferraris the pleasure I get from just sitting behind the wheel and looking at the Cavallino, sure beats Stars, Tridents and so on.
On the way home, between the Goulburn turnoff and Braidwood, it is a two lane road, with few spots to overtake. Coming up on a couple of caravans travelling at 80-kph on the twist bits and 90 on the straights I gave the car a go. No cars ahead for at least 300m. .. paddle down to 3rd .. accelerating slowly until pull out then pedal to the metal .. I have NEVER NEVER been in a quicker car.
I would never track this car, as I have others .. it is a GT car, as a car for the relatively polizei free roads around here it is soo much fun .. I even like the paddle shift. My desire ultimately on my bucket list is to go back to a GTC but I would recommend a 575 with a paddle. Unlike FF I much prefer the interior with the huge Tacho and better dash layout. The rest seems much the same.
If you want to have track fun get a Formula Ford at $30K., I would NEVER buy a car that has been tracked.
PS Car is NOT for sale and I am not paid to say this