I had one made about 4 years ago for my 1986 510TE, having run auto Huskies for years and a modern 300 GasGas with a Rekluse clutch I thought it would be a good idea. After much money being spent, about £600, I ran the 510 with the modified EFM clutch in a few Enduros here in the UK. To be honest I wasn't that impressed, nothing like as good as the Rekluse on my GasGas, felt very lumpy in the 510 so I suppose the 610 would be even worse. Went back to the normal clutch but felt disappointed that the EFM one didn't come up to expectations. If you could persuade Rekluse to make one of their latest offerings to fit the 610 I could be tempted to have another go.
I would just get a 6 speed gear set off of ebay and switch it out, way more versatile. You will need the shift drum and shift forks as well. I did this to a friends TC 610 and it transformed the bike in to something great.
used EFM on my 125's and 310 great....no wear or binding ever. 610 is not a wicked motor so it will feel smooth. cannot compare an auto clutch in a 2 stroke to a 4 stroke
Although it was on 2 WR125's, a WR144 and a WR165, but not a 610, my experience was just the opposite. You can say only a tiddler and less torque, but the EFM performed flawlessly. On a small bore you need to use the clutch manually to keep the bike in the power. The EFM worked great, with total modulation and smooth engagement feel. Friends with KTM 150 and 200's with Rekluse always had modulation and engagement problems.
