The specs say 7000 lb and 8000lb displacement, waterline length and designers are the differences.
C&C built 5 versions of 27' similar layout but different in dimensions/specs and therefore performance/speed and space. I ended up with a Mark 2. The Mark 5 is almost 28' long, much faster, has a wheel and diesel and a built in garbage can in the galley versus my $10,000 less expensive version! Oh, and mine was overbuilt with 1970's fiberglass layup techniques that are far less prone to deck problems the Mark 4's/5's have.
I suspect performance/speed,and space are the main differences. If you sail on the Great Lakes there is a $30 annual license for Canadians to buy on 30'+ footers visiting US shores versus 29' - 11.4". So, who knows what the owners said when registering their boats upon resale????? Oddly the following sites say the 29 has a longer waterline length than the 30 so the 29' Mirage would be faster (all else being equal).
Sailboatdata dot com - Used Sailboat Market in Canada for a simple spec on the 29 and 30 footer.
There are the 29' Phillippe Harle design and the 30' a Robert Perry design there.
When you fiqure out the finer differences email me. I like the boat, (sister ships are in good shape at our club), they are fast. The only issue is delamination around the main hatchway in a 27' I almost bought. ([email protected]
Try the want ads on boats for sale and ask the owners or each creed to tell the differences.....