spiral mixer

hey guys, 

So im hearing alot of talk lately on fork mixers. why is this? are they that great? what is wrong with a spiral mixer? 

I've been making sourdough my whole life using a spiral mixer, why would I be now getting told that I should look at replacing my faithful spiral for a fork? will it make a difference to my doughs, or my bread for that matter? 

I just want to hear what peoples thoughts are on this topic as I know nothing about fork mixers.

Thanks