1) Independant speaker level control - 880 has it, cd7100 does also. 9887 Also has this feature.
2) Independant phase control for each speaker - 880 has, cd7100 doesn't. I don't believe the 9887 has this feature as I tried to find it in the manual and do not see it.
3) Full subwoofer control - Level, phase, mono or stereo output - All three units have these controls.
4) 15band eq on 880 was very nice, the 11 band PEQ seems to be more customizable and a great feature, I definately prefer the PEQ over the 15-Band with the customizability. 9887 gives the option of a 5 band peq or a 7 band geq, this is a great feature, you can adjust if you have peaks at certain frequences, or just use the factory geq to adjust fixed frequencies. The best of both worlds you might say. One downfall though is that the peq can only be adjusted > 4 steps of each frequency.... kind of a crappy deal there.
5) 880 only had the 15band, CD7100 has Bass, Mid, Treble controls as well as the PEQ. This is a nice touch. 9887 read #4.
6) 880 has built in aux in a kind of unorthodox place though on the bottom of the faceplate, stupid IMO and no built in USB, CD7100 has both but the interface is kind of blah on the USB and I have not yet tried out the AUX though. 9887 requires external adapters to use both functions, somewhat pricey, ipod connection wire is fairly inexpensive though.
7) In active mode: 880 full subwoofer control - CD7100 Non fade with level control when in 3-way mode/ stereo mono selection as well as phase reversal. 9887 retains the same subwoofer controls in either mode, with phase, level etc. There is also a 2nd subwoofer system setup which allows the user to get more volume from the subwoofer system, as well as the MX media expander function which affects the sub and soem of the higher notes (based on the manual).
8)Area shot feature - this is a pretty neat feature to throw into the mix that Eclipse has. I got it to work the other day and am very impressed with it but it is not like navigation unless you add the gps unit. It's a good backup feature but along with it I would always keep a couple of backup maps etc. Works decent though.
9) 880 comes with a Mic, CD7100 does not, not THAT big of a deal however it is nice to know that you don't have to purchase anything additional in order to run the auto TA's etc. 9887 has no auto ta, unless using the IMPRINT.
10) cd7100 lets you adjust TA in steps by millis second, pio only does this by distance in either centimeters or inches. 9887 adjusts by calculated values, requiring some leg work by the user, though they do provide a nice guide within the manual for conversion.
11)E-iSERV data can be uploaded from either the unit to the pc or the pc to the unit and you're able to fine tune right from your pc. You can setup a flat FR by adjusting the PEQ on-line and saving to USB then uploading that data to the HU, you are then unable to adjust any of the TA settings on the UNIT itself, which is fine, just a quirk. Similarly alpine has the imprint, however this cannot be utilized for free of of a website, instead requires purchase/rental (crutchfield) of outboard mic and software.
880's intereface is straight forward and very easy to use. The CD7100 is a bit more complicated and I feel as though I have yet to tap into the full number of features that it has or am just not sure how to use them yet. 9887's interface is very nice. I thought it would be a pita to navigate as many have stated however I was used to it within 5 minutes. It's logical and setup quite well.
Fit and finish: 880 was alright... nothing to scream home about, issues with the face being loose, and on mine I noticed the screen would go out once in a while for maybe 1 second or so. cd7100, I was not impressed with the fit and finish of such a pricey unit. It had similar feel of its motorized face, required a strange mounting style in order to allow the face to open properly and to remove and play discs. VERY big pain in the a$$. 9887 No motorized face, doesn't feel loose or sloppy, super tight solid feel to it, excellent feel. Recently purchased an 800prs and the face does not feel like it did on the 880, so maybe they tightened it up or there was a problem with the 880 I had.
Here's the most important part - SQ -
880prs has a much more warm/soft sound vs the CD7100 which was an in your face type of sound. the 9887 couples both of those, its warm, yet rich and powerful, it's not as in your face as the cd7100, and not as laid back as the 880prs, I'd call it a happy medium.
All three units really have strong pre-outs, the 9887 sub channel is a bit weak though. 9887 - Although rated at only 4 volt at high impedence I must say the 9887's outputs are VERY strong. They are similar in sound to the ear to the CD7100 which claims 8v. The premier has good preout voltage I had a line driver on it, but that was my mistake because I never went past 30 on the volume control which if I had I would have realized I did not need the LD.
The 880 prs had very consistent sound, I never felt that I had to have the volume up extremely high just to get output... the CD7100 at times required me to turn the volume up to 65-70 out of 80 or so just for it to be loud and consistent... 9887, I've never had to go higher than 15/20 to get good output.
All three are very good units, however it's clear that some of the attention to details is superior in the 9887 vs the CD7100 as well as the 880prs. I went full circle and ended up with the 800prs in my car again. I prefer the soft/warm sound it has versus the other two units and the consistency in sound playing different media makes me a happy camper.
Those are my impressions so far, maybe more to come if I find more features etc.