Just get what you can afford you will be happy with either one.
This is what make's the 2011 different
Improved exhaust
Improved heat exchanger
Electric power steering
AL block
Standard HID's
FGT Blue Valve covers
FGT SC finish
10 additional HP
No gas guzzler tax
Chassis and suspension improvments on convertiable's 30% stiffer
1 mpg better
120 pounds lighter
Improved brake cooling
Improved underbody aerodynamics
Improved sound detoning
Improved SYNC
$1,800 increase over 2010
Optional
3.73 gears
Lightweight 19" and 20" rims w/ bad ass tires
Improved shocks and struts
Improved sway bars
Lower springs
Adjustable rear spoiler
Unique Shifter ball
Unique Stripes (optional)
Unique Color combo's
Glass roof
If you're like most and like the look of the 2010's WAY better dont worry because the 2011's look 100% the exact same way, and differences you see are optional equipment.