Hi Fish,
Not wanting to steal any sales from the good folks at Nokta Makro....
My personal opinion is this, and, please bear in mind I have the FORS Relic and the Impact units and
zero experience with the Anfibio.
For me the salient/deciding issue is do you need or want a waterproof detector or not?
If you are routinely hunting in a downpour, and do beach or shallow water hunting then an Anfibio, (or Kruzer/MultiKruzer), are your best options. Obviously the newly released Anfibio will be the priciest option with maybe somewhat better menu structure and crisper audio to quote those who have been using them in the development stage.
Alternatively a Kruzer or MultiKruzer sold with some useful accessory coils & lower stems will be a better bang for your buying buck as the original purchaser is probably selling at a significant loss to change over to a, (the), newer machine.
If you primarily hunt in good weather and need target separation, quick recovery speed, and decent depth, then I think a used Relic package with multiple coils may be the most cost effective,(you may be able to get one new on clearance also). If I were to part with one of my Nok/Mak machines I would part with the Impact before the FORS Relic, no slur to the Impact but I have bonded with the Relic personally.
Another consideration I keep in my mind is that the Nokta Makro folks may be on the verge of releasing their own version of a simultaneous multi-frequency detector, so buying used now may allow more funds for a game changer down the road a ways.