Another shameless plug, but I have an X&M crossover blender for sale!
Standard blenders are great for adding a [i]bit[/i] of low end back in, but if you dial in too much clean it sounds funny with two clearly separate signals going on. I prefer to use this type of blender with fuzz pedals that already have decent lows, but just to add a bit of clarity and dynamics to the heavily compressed signal. Even better if you send a lightly overdriven signal into the blended fuzz, it sounds much more meshed together that way. If it's a lack of low end you're trying to make up for, I'd go for the Xotic X-Blender over the LS-2 or Barge since it has an active EQ built into it.
This X&M does it a bit differently though as you can keep the lows totally clean and send everything above that to the distortion pedal and adjust the levels of both channels, mimicking a recording setup where you blend a low-passed DI signal with a mic'ed cab.