I do not have the Impact, but do have a lot of time on the Anfibio Multi. The Anfibio is an excellent all around detector and has slightly more raw power/depth than the Legend. The Concentric coil choices are useful also. From a practical standpoint the Legend offers much better stability on difficult ground, in Iron trash or in EMI. This allows you to be able to run near maximum if you want/need to. It is very rare to be able to run the Anfibio above 90 except in 3DI. The Legend has much better TID along with excellent audio intelligence. The Anfibio is primarily an audio machine unless the targets are clean. The Legend's added adjustability is also very useful. As far as big coils. the 35mm coils for each are excellent. The Anfibio's KR40 is too heavy to be practical for me and not really any deeper/sensitive than the AF35. I have no intentions of retiring my Anfibio, but I have 2 Legends & they get used a lot more.