I just installed a set of these in my truck last night and was waiting to do a full review after I had some time to get a good feel for them. I yanked the RSDs and threw these in last night and got a couple good hours of listening on them today, but obviously they are far from broke in. I have 150wrms slapped on them and they handle it no sweat.
Definitely more efficient than the RSDs, had to turn the gains down from where they were. The midrange is very detailed, yet more mellow than the RSDs--the vocals aren't as overpowering/harsh as the RSDs in my install. Very balanced is how I would put it. You dont feel the need to tune everything so much and make cuts/boosts up and down the line. I am running my settings dead flat right now and they sound great. Not wanting to push too much lower bass material to them until they break in more. The midbass on them is fantastic though. Eric Stevens the ID rep and I discussed this at length and he felt the midbass/range was the strongest selling point of this kit, and had a lot of value given their price point. They put a ton of time and research into them just like their other sets--the reason they are cheaper is they are Chinese bult, unlike the others. The built on mine appeared to be superb though.
I like the tweeter about the same as RSDs. Not picking up much difference at all in that regard. One thing I would give the RSDs the nod for right now is that they seem to be able to handle more
I would certainly recommend them to anyone looking for a set in this price range. One thing about it is that being IDs they will have great resale value if you ever decide to sell them. If you want a lot cheaper set that really impressed me, check out the Cadence CWM6 set, it has been getting some good reviews, and knocked my socks off when I put them in a friend's truck the other night. They are $75 shipped. The IDs are better, but probably not $100 better. I bought mine authorized from woofersetc.com for $179 shipped. For $130+ shipping, go for it. Just make sure you got enough power to wake them up.