I apologize for this long, long post.
Something else is going on cause with your resolution 800 should be slow and 1800 more normal but not enough. Did you turn off mouse acceleration maybe that is the problem. If that's not the case then you need to get used it.
DPI is a hardware based sensitivity. It's better to raise DPI and compensate by lowering sensitivity to avoid software or more precisely in-game sensitivity control. Calculation though crude is Old DPI*old sensitivity/New DPI. Though it depends on the game, some of the older games get negative acceleration from higher DPI.
Say you used 800 and 1 sensitivity and you bump up to 1800. 800*1/1800= 0.44444444444444444444444444444444.
Also you speak of cursor precision. Despite what some people will say. I've spent tons of hours researching DPI and from what I've gathered higher DPI is more precision. First to attain 1:1 movement in a higher resolution i.e. pixel precision to current higher resolution for desktop and or in-game.
Second of all if we do some math and convert an inch into MM we get 25.4 or 2.54cm. 25.4/800=0.03175mm, in other words at 800 DPI your mouse is reading with in this range. 0.03175mm is half of what 400 DPI is, being 0.0635mm. 25.4/1800=0.014111111111111111111111111111111mm, 25.4/3500=0.0072571428571428571428571428571429mm; with 5700 it's 25.4/5700=0.0044561403508771929824561403508772mm. You might be asking yourself what does this all mean. Aside from becoming faster both in pixel movement per inch and when that measurement is read. It's more accurate because it's reading at smaller and smaller intervals of millimeters.
A more simpler approach
http://hardforum.com/showpost.php?p=1035470202&postcount=20 and
http://hardforum.com/showpost.php?p=1034229686&postcount=39Now your resolution is 1920x1200(I'm guessing you left out the 20). To have 1:1 movement i.e. DPI based on inch. You need 1920 on the X-axis and 1200 on the Y-axis.
I know some people will say it's an RTS precision doesn't matter just speed but remember you don't want to exert so much effort to move around that you suffer from fatigue. Plus if your good at noticing pixel skipping to achieve a speed of what high DPI will feel like, you usually set the in-game speed higher and end result is 450-800 is going to require pixel skipping. It doesn't matter whether you set windows to 6/11 it's going to reach the end somehow. So it'll do so by skipping or read all 1920x1200 in between 4-6 inches of movement, instead of the usual 1 inch with say a lower resolution and a mouse equating said resolution. Like for example 800x600 with an 800DPI mouse.
In other words would you rather have low DPI+higher sensitivity or high DPI+lower sensitivity. Lets say 400 and 2 vs 800 and 1, both feel exactly the same; the difference being is say you used 800x600 the 400 DPI you need to move 2 inches to complete 800 when set at say 1 while at 2 it reaches 800 but it does so by skipping.
Unfortunately both mice aren't all that suited for FPS gaming but for RTS I've read they alright quite popular with Asian gamers or those with smaller hands.
Sorry if I've gotten out of hand, I could probably go on and on and on with what I've read. I know I mostly speak out of an FPS gamer's perspective, but it doesn't hurt to translate some of the information to other games. I've done tons of research, just tons on DPI and mice. I know it's an RTS but still it doesn't hurt to know.