I did the double-edged safety razor thing for 10-15 years, on and off, occasionally trying the latest cartridge from Gillette or (more recently) Dorco before going back.
A few months ago, I tried the
Dorco Pace 7, and I've stuck with it. It's the best razor I've ever used. There's a surprisingly large difference between the six-blade system and the seven-blade system. The seven-blade cartridge gives a much easier, smoother, closer shave, and the blades last a lot longer as well.
Try the 7. You can use the same handle as the 6 Plus, just get the cartridges for the 7. See if you get the same results I did.
While you're at it, try
Cremo. It's very cheap and is the best shaving cream I've used.