I've used both extensively. I had an EU3000is (not the Handi version) for about four years and replaced it with 2 x EU2000i, in use for six years.
There are pros and cons for each. The main pro for the 3000is is that it's easier to listen to than 2 x 2000 when running an a/c or otherwise at high load. Per Honda specs, it's only marginally quieter, but it's a huge difference in real life. The pitch is lower, the rpms sound lower, and it's one unit at 58 dba (at rated load) vs. 2 units at 59 dba. The sound is simply much less intrusive.
At idle or low loads, the pitch difference between the 2000 and 3000 isn't as noticeable, but the 3000 is much quieter. Honda shows 49 vs. 53 dba at 1/4 load. This is a HUGE difference especially if I'm running both of the 2000 units.
The main con of the 3000 is weight--and this is why I got rid of it. At 130+ lbs, it is difficult to lift in and out of my truck compared to the 2000 at 46+ pounds.
For the EU2000, the two main pros are weight and the fact that I only need to take one small/light genset with me if I'm not planning to run the a/c (...though I rarely take just one these days...I have 2 x 6v batteries and all LED lights, so our family of four can easily go 4-5 days w/o charging the batteries....now I typically take the gensets only when I think we'll need a/c).
The main cons of the EU2000 are noise level/quality and maintaining two gensets vs. one.
The bottom line is I much prefer the EU3000is because of noise, but I think I'll stick with 2 x 2000 because they're easier to move about. Honestly, it's a close call.
FWIW, I'd be careful about mounting a lot of weight like generators on the rear of your trailer. It should be in my posting history, but I had the EU3000 mounted in a box and took the time to have things reinforced. I still ended up bending the trailer frame near the axles in front of my reinforcements. The load was simply transferred forward and the frame couldn't handle it.
