I just worked through the same dilemma...that is, using flex, bending and shaping for the first time and making a jig (hoping each piece will come out right), or taking the "price hit" by buying sectional curves one time only. I chose to take the hit and bought the sectional curves. I purchased 12 pieces of 072 and 12 pieces of 063 Gargraves...the curves look great!
In working on my projects, I prefer to get to the end game quicker without a long process. As mentioned above, cutting the track to get the joints tight can be tricky. I've cut plenty of track on my previous layout. The system I developed is simply screwing down the track to a bench while leaving the area to be cut slightly overhanging the end of the bench...makes is easier to get a straight cut with the Dremel.