I only use ergo keyboard . ca not use flat one , since my forearm go numb within a half hour . I buy the m natural Ergo 4000 kb to replace a aging ps2 no-name kb . I really do not need to , my finger fly on the old kb , but want usb and want a bit quieter key . my typical go-to company for accessory like these be Logitech -lrb- just do not order direct from Logitech ... go Amazon every time -rrb- . however since Logitech do not have ergo keyboard -lrb- no. . . they do not have ergo keyboard ... the wave crap be just a wavy non-ergo kb ... I repeat Logitech do NOT have ergo kb -rrb- ... hmmm where be I ? I digress . oh yeah ... since Logitech do not have ergo kb , the Microsoft Ergo 4000 seem to be the most popular one . Thought I would give it a try . quick summary ... I be go back to my old ps2 no-name kb . here be my observation on the m Ergo 4000 . pro this kb be very quiet , which I have come to like . it also have very nice function button that you can use to launch a browser , calculator , zoom in and out , and do other function . it be black , so show less finger grime , and I like the cushion wrist pad . the bottom of the kb elevate for proper typing posture -lrb- I still can not fathom why anyone elevate the back of a kb !!! -rrb- , and the split in the key be very comfortable for I . con -lrb- for I , unfortunately they outweigh the pro -rrb- \* this be a non-gaming kb . now I do not need a specific `` gaming kb '' to play game , but I do need to be able to press more than 2 or 3 key simultaneously . with my old ps2 no-namer , I could do that . however , with the m Ergo 4000 I can not . for example , I crouch -lrb- ctrl -rrb- and move forward -lrb- up arrow -rrb- . if I try to move diagonally forward while crouching -lrb- ctrl , up arrow , LEFT or right arrow -rrb- , it will not work . I just keep move forward . I can crouch and move a single direction , but I can not crouch and move diagonally because that involve 3 simultaneous key press , which the m Ergo 4000 do not support . \* hate the main ENTER key . my ps2 no-name kb have a large reverse-l-shaped enter key . I can smack that thing when I be typing or gaming ... can not miss it . I type very fast too . the ENTER key on the m Ergo 4000 be a small horizontal bar , not a larger reverse-l-shaped key . the backslash key be directly above the ENTER key . I would say 50 % of the time I hit the backslash when try to hit ENTER . in 2 month of use with the m Ergo 4000 , I can not overcome the smaller enter key . it be even worse with game , where I need quick access to the ENTER key . half the time I miss it or I hit multiple key . \* on my ps2 old kb , the backslash be under the ENTER key , and I use that key for game function -lrb- I game with mouse and arrow key , not with WASD key -rrb- . I find the backslash key on the m Ergo 4000 to be place in a inconvenient spot . this be more of a niggling issue , as most kb have the backslash above the ENTER key , but I like my old kb 's placement of it under the ENTER key . \* the space bar on the m Ergo 4000 be generally okay if hit near the middle area , but toward the outer edge it stick and will not press . this be not a issue while typing for I , since my thumb hit it just right of center . however for gaming , my left pinkie finger hit it near the right edge . maybe 20-30 % of the time it catch and will not press when I hit it during a game . \* the esc key on the m Ergo 4000 be just below the browser launch button . with my older kb I can hit esc without look at it . in fact , I be very attuned to the key placement on my older kb , and can hit just about any key anytime without look . with the m Ergo , I hit the browser launch button about 40-50 % of the time unless I be look for the key with my eye . that be about it . it be a decent kb , comfortable , split very well , and quiet key . however , I can not overcome the smaller enter key and the lack of multiple simultaneous key press for my gaming activity . I have go back to my older ps2 kb , and will probably stick with it until computer no longer have ps2 port ... then I 'll get one of those more pricey ps2 to usb adapter . unfortunately , no one make a ergo split kb for gaming specifically that I can find . at least one that meet my criterion for gaming , enter key , etc. . would love to see Logitech make a split ergo kb -lrb- again , that wave stuff be not ergo -rrb- , but company really be not too concerned about make really reliable , good ergo split design . the m Ergo 4000 be a exception , and it be a good kb , but just do not fit my need . if they redesign with the larger enter key , and maybe 4-5 simultaneous key press support or better , it might be the perfect kb . until then , I 'll stick with my try and true .