Hi Jani,
I have just finished installing this exact thing on my 620 this weekend. I didn't have any real issues, everything went well but it was several hours work because I took my time with it to make sure everything went on right. Only thing to note is that when I bought my bike the previous owner had installed longer brake lines already because she had some tall risers on the bike. Therefore I'm not sure whether you'd have any reach problems with the standard lines etc.
You will see from the pics that the speedymoto top triple is about flush with the top of the forks - the forks are about 1mm through the top.
My forks were dropped through alot further for a while when I had the standard triple and handlebars set-up - I didn't like that set-up it just never felt right. Also, with the forks dropped through the front always felt a bit twitchy in corners.
I didn't get a chance to go for a proper ride after finishing the install, but I liked how it felt so far with a quick ride. Much more natural hand position, and not so wide of a reach. I'm also hoping for much more stable handling but I won't know that until I get out for a proper ride.
I have read other posts where taller people have said that clipons feel better. I'm only 5' 3" and the new set-up feels much better for me too.
Hope the pics help. Let me know if you need any more.
Cheers
Liz