Having both...I'm tempted to say C74 over the M200. Whilst the Pelikan does have the piston filling system, cleaning the pen out is a hassle, and honestly, it bothers me a bit that ink tends to get stuck behind the piston once you start using it. The Pilot does have a slightly springier nib, and although it is c/c, if you get the CON-70, or even the CON-20, you shouldn't be running out of ink too fast.
Furthermore, I believe you can find the C74 online for better prices than you might expect for the Pelikan. I also find that the Pelikan M200 series nibs are quite smooth, and are very nice, but have this strange....almost ballpoint feel to them.
Size is another factor to consider. If you like posting your pens, I would go for the M200 - it is on the small side unposted, though. The C74 is larger, and better unposted. I do have small hands, so I use both unposted...
Also, the demo versions of the M200 command a price premium, I believe the C74 comes in both demo and solid colours for around the same price. There's also the Pilot Custom Heritage 91, which has the same nib as the C74, is about the same size, but has a different design. It has the classic flat-top design, and a different clip, but I have found them to perform similarly. They also tend to be cheaper, but only come in solid colours.