This is purely anecdotal, however, I've had pretty extensive time listening to the Event 20/20s, I've also put a fair amount of hours on some Rokit RG8's and Yamaha HS80m and HS50m's. I personally don't feel that they were all that accurate or flat for that matter. I have spent the most time with the Events and I felt the 20/20's were quite harsh. I've used the Rokits quite a bit as well and felt they were the funnest of the bunch but certainly far from flat (you are asking about a different line in the series though). It's been a while since I heard the Yamaha's but from what I recall they were similar to the Event's. Granted I didn't have the chance to properly A/B/X test these so take my experience with a grain of salt.
There is a really interesting read on Audio Circle talking about studio monitors and accuracy. It might be worth a look.
My general feeling is that the studio monitors are not really all that flat but they are purpose built for one thing and that is helping what you mix translate onto systems people will be playing your music on. As I understand it, most studios are trying to mix what will sound good on an average persons systems which is why we are plagued with things like compression and the loudness wars etc. I don't know that perfectly flat response is what they are most concerned about but rather how the mix will translate. Since you're interested in production, the monitors you listed may be exactly what you want. I feel that the Event's specifically have really piercing treble which may help to pick out issues with your mix. However, I don't feel they are anywhere near as good at pulling out subtleties and details compared to some other solid passive speakers. I guess what I'm saying is that you may be mixing up two things, the first being accuracy as in flat response low coloration/anomalies, etc, the second being accuracy as in how it will translate to common systems. If you are looking for something that may most accurately represent how the music is recorded without adding anything to it, then some passive home audio speakers may be better suited. I know there will probably be many here that disagree with me but this has been my experience and that's not to say there are no studio monitors are great and being flat and uncolored.
My recommendation would be to see if you can audition them with the type of music you are mixing/producing and see how they sound to you. It may take some trial and error but i'm guessing you will learn to mix your music on whatever monitors you get and know how it needs to sound on your system to make it sound good on the majority of other peoples systems :)
Edited by ryant - 6/27/14 at 9:11am