my own two копейки

i honestly tried--it looked like a good idea for street so i wanted to make to work. the DW-1 on F2 was for all practical purposes unusable. the only advantage over simply taking off the regular prism was the flip-up magnifying glass--but then, if you're prepared to squint up close, the angle attachment is much more useful (i use it for slide copying, macro, tripod work, etc.)

DW-2 is good, but definitely more for studio than street

overall, if you're also just thinking "it looks like a good idea" with no specific use case in mind, try it out before you commit. these finders are easy to buy, hard to move later--and for a reason i guess