I am a recent new owner of a Sony HX850. (Hi all!)

I think this TV has really good potential, but I am worried about some PQ issues. I have a Sony Bravia XBR-Series KDL-40XBR2 (now moved upstais) which still after 5 years is pretty damn awsome in quality.
First of all the real good about this TV as I 'see it': The PQ on cable box 720p channels (ESPN), blue ray and dlna streaming is really good. As noted here in many posts, there are some gems in the settings that you'll need to tweak, noticably 'full pixel' mode, Cinema (color warmth depends on your preference), white balance the blue down a notch and work out your backlight, contrast brightness and turn off some of the useless smoothing style options. So, after tweaking around with this using ESPN as a benchmark, I was pretty happy. The DLNA and networking was a breeze to install, and the PQ on streaming movie content from my PC is really nice, even some of my 'less acceptable' movies in lesser mpeg qualities still look very very accceptable on the TV.
The sound is not the best, the equalizer allows you to make it a bit more acceptable, It pales comapred to my XBR, not a biggie, I will likely get me a sound bar (
almost inevitable with current super nimble LED designs, no room for decent quality speakers and woofers / sound design).
Now the thing that has me worried is the PQ on 1080i. Once I was happily done on ESPN tinkering with the settings, playing with the DLNA, internet and all that, I started flipping to my cable box. (CableVision Atlanta HD DVR, HDMI). Now, most of my HD channels on the cable box are 1080i, and the PQ on these channels is not very good. The colors look off and all cripsness and contrast (that are there on the 720p) are 'dead'. The screens looks way to light (not the right kind of bright, more hazy /milky as if the brightness is on max). Depending on the general color tone of the channel or picture, the picture looks bluesih, purplish or yellowish white.
I went through and toyed with all settings (and tried additionally Cnet, panel review and serttings posted in this forum), worked with the ECO on/off, backlight corection, trying all different features, tries scene Auto, auto 24p (which would work out to autro on 1080i?), Cinema (setting cinema 1 and 2), but I can't get it right. The only way to get it kinda acceptable is turn off the eco settings (as most here advise), backlight at about 5, yank up picture to 90 or max, and turn brighness down to about 40. But it still 'too light' and colors are still off. Chaging colors warmth to 'Warm 1' makes it a bit more 'yellowish'.
I am wondering if there is someting wrong with this set and if I should return it? There are no other issues that I can see, a slight (normal) blooming, no bleeding, no bad pixels. It makes me wonder if this is just 'as good as it gets' on 1080i and the TV's engine and software are dedicated on 24p and simply not doing a good job on interlaced signals?
I also tried toying with the pro options (Color Matrix) and bit mapping on/off, etc, but other than suspecting 'some' effect, I fail to make it look right on most of my channels. The 1080i channels simply look way better on my older XBR.
I will likely check with Sony first and see if there is any remedy for this as I am still in my 30 day return window. I recently returned a Panasonic ET5 that did not live up to my PQ expectations, while this Sony is better, I am not sure if I am happy enough with the 1080i as it is now, and having spend 4 nights tinkering and researching all my options on the internet (great forum here btw!), I am not sure if this can be 'fixed' or is simply nowadays state of LED TVs?

Any advice and comments appreciated, hope I'm not too much a debbie downer, I really want to like this TV as much as I love my XBR!