Is a dual extruder a reasonable choice for all-purpose printing I'm new to 3D printing and I recently got a LulzBot Taz 6 printer.

I'm interested in doing dual extrusion printing (especially with dissolvable supports), but I'm also interested in doing single extrusion prints. In particular, I would like to experiment with printing flexible filament.

The LulzBot TAZ Dual Extruder v3 Tool Head says that it can handle all the filament types that I am interested in.

Here is the question: can I use a dual extruder (in particular, the LulzBot TAZ Dual Extruder v3 Tool Head) for general purpose printing (read single extrusion) or do I need to use a single extrusion head for single extrusion print jobs.

If you can use a dual for single use, why buy single extruders (I've been looking at LulzBot TAZ Aerostruder Tool Head for flexy prints) if you can get the same performance out of a dual head?

If you should use a single extruder for non-dual prints, please explain the shortcomings of using a dual print head for general purpose use.
Not an expert by any means but I can’t see any reason you couldn’t use one half of a dual extruder. The benefits of not using one though would be decreased extruder weight. Especially given that this is a direct drive so there will be two stepper motors I believe. Reduced weight means faster print times and a reduction in certain print artifacts such as ringing etc.

Short answer, if your only ever going to need one extruder probably avoid a dual but if you want the flexibility this should work when a single extruder is required.