I m using 1152 X 864 & I can see difference too.I dont know what I feel exactly ,but I was expecting little more.Original Blueray mov can look stunning.I can just get as sone DVDs look dull & some good.
PowerDVD cant open those,but lattest VLC can.
So with 1152 you are already limiting the horizontal lines which is max 1280 for 720p and 1920 for 1080p.
You will not get the full potential of 720p movies on your screen. And 1080p movies will seem same for you. Moreover you have small screen, so you may not be able to judge very correctly, about the DVD/HD differences.
KMP + haali + CoreAVC also improves it.