The Digisix/flash are slower to setup when you change films, but once you have done so, they are quick and easy to use. In my mind, the time I save because of their incredible portability pretty well offsets their slowness of setup.
I think they are quite robust, and that their tiny size contributes to that. I am quite sure that the combination of their versatility and their tiny size is what causes them to be as expensive as they are - if they were bigger, they would be cheaper.
In my case, I'm happy to switch back and forth between my Profisix and my Digiflash, and to appreciate both of them for their strengths.
As to whether it is a good idea to spend the extra for the Digiflash vs. the Digisix, it seemed to me that when I made my choice I was acquiring the meter because of it's compactness, so it didn't make sense to have to bring two meters at any time when compactness and flash metering both mattered.
By the way as I recall it, when I bought my Profisix new in the 1980s, it cost me more than the Digiflash I bought recently. If you include the cost of the Profisix flash metering accessory I bought shortly after I bought the Profisix meter, the two together cost much more than the Digiflash.