I much prefer the mixing approach to blending. I have a OneControl blender and it is ok for what it does (tiny bypass loop with buffer and phase inversion). The better approach is a true mixer like some SFX offerings or the Wounded Paw "blenders". I use quotation marks because they are mixers, not blenders. The problem with a traditional blend knob or separate blender is that you take away from one signal to add another. A mixer will let you keep one signal at full strength and add a bit on top of that or do something completely different.
The wounded paw blender is great for mixing crazy sounds together, inverting phases, EQing, changing levels of loops on the fly, etc. For actual low end, a pedal with low end retention and/or good EQing will always be a better choice...