I bought a Targa with the intention of converting it to a cabriolet later, as it's not too complicated a conversion and you save some cash.
The first weekend of driving it was enough to convince me to abandon the plan. I was just astonished how much of a cab feeling you get in a Targa, but with the added advantages of the rollover hoop, better rear visibility and better security. (Especially with my Pelican Parts fibreglass roof, it isn't obvious to a thief that the roof is removeable.)
More here:
http://www.nurburgring.org.uk/benlovejoy/wheels/911/roof/
Ben