I wouldn't recommend WCing the mosfets and chipset. Typically they are adequately cooled by their default heatsinks, and even with overclocking they don't get any substantial benefit. That money would be better spent on a better GPU, CPU, PSU, more memory, ect.
Even if you watercool everything in the computer you will only need one loop, especially if you use a powerful pump like the MCP655. Two loops is only partly worthwile if you have a heavily overclocked CPU with a high end SLI or Crossfire setup. Even then simply adding another radiator or two will be a better investment. Dual loops will of course need two radiators anyways, but an extra pump and fans are also required.
You may be thinking of simply splitting the pipe in two, one for the CPU and one for the GPU. But this reduces pressure and flow rate through the waterblocks, which may reduce performance. Another possibility is that one block is very restrictive, the other is not. This leads to less fluid to the restrictive block, further increasing temps.
I assume that the Reserator gives you acceptable temps as you state no plans to have it replaced. If it isn't though, you may want to try the Thermochill PA120.x series. With an S-Flex or Nexus fan they are excellent choice.
Using the MCP655 will likely lower your temps on it's own. It's a very powerful pump. You have the MCP655-B though, it has no speed control, so it always runs at full power. The non -B version has speed control, but costs more. You may find the noise from the full speed MCP655 unacceptable.