the thing about fixed side by side dual extruders is this:

1) Unless PERFECTLY levelled one head will always catch on the print at some point and bugger it up.
I actually sand off any protuding filament from the nozzle I'm not using for aprint to make sure there's nothing there to catch.

2) you need a REALLY good purgewall for dual material prints. this is used to collect dribbled filament from the head that's just been used and clean up the head that's about to be used. you end up using a a lot more plastic and almost doubling the print time. I have never managed to get simplify3d to work with dual extrusion.
I use flashprint, which works fantastically well :-)

3) calibrating dual printheads is a real pita. The only way I know to do it is with replicator-g, and it doesn't work that well. Fortunately my klic-n-print has so far managed to work without it being done.

4) 2 or 3 into one systems look good, but bear in mind you have to have the same print temperature for each material. with a proper seperate extruder setup you can have two completely different materials with different print temps. Although mixing things with widely varyong temps is not a good idea, as the hotter one will melt the cooler one.

So because of all this - you rarely use the dual print option.
My first printer was a flashforge creator - before flashprint and simplify3d existed, so I was forced to use makerware desktop as a slicer. it works well for dual prints, but is the single most difficult and obstreporous slicer to adjust and setup out there.
The klic-n-print went largely unused (won it in the first and only 3dprintboard.com competition) - despite being the better printer - for quite some time.
Now the creator is ill and in limbo until I get the inclination and time to fix her. And I'm now using the knp a lot more, mainly because of how easy flashprint makes it :-)

So taking all that into account, idex takes all the hassle out of it. essentially you're just dealing with two single extruders, which are (presumably) calibrated seperately.
Not cheap - but worth the investment.
If I had the money and deskspace I would get one of these:
https://technologyoutlet.co.uk/produ...x-2-3d-printer

If I won the lottery I would get one of these with the hi-temp nozzle option: https://www.lpfrg.com/products/leapfrog-bolt-pro/
Out of the hundreds of machines I've seen at the tct shows over the last 5 or 6 years, this is still my all time favourite.