I'm going to be buying the 990/7125/LFM-1 combo.
I've been reading the reviews of the different remotes to use with the 990, and a lot of people have said good things about the MX-500.

Are there any major differences between the MX-500, MX-700, MX-800, MX-950, and MX-1000?

By the way, there is a new MX-650 and MX-850 comming out this year.
Too many choices.

The MX-500 and MX-700 are being discontinued. I've got reviews of both of them on my site ( 500 and 700 ). The MX-500 does not have a computer interface, has half as much memory as the MX-700 (ten devices and two pages per device rather than twenty devices with four pages each), and has limited macro support (five macro buttons, basically). In addition to the extra memory and computer interface, the MX-700 allows any button to be a macro. The MX-600 is an MX-500 with RF capability added; the MX-800 is an MX-700 with RF. The MX-650 and MX-850 are probably going to replace the 600 and 800; the only difference I know of is the navigation pad (the 650 adn 850 have a completely separate select button in the middle of the four-way pad). The MX-1000 is an older design that I wouldn't mess with. The MX-950 and MX-3000 are basically aimed at the same market as the Pronto remotes (custom installers and folks willing to drop up to $1000 on a remote). I hadn't noticed the TX1000 until just now - don't know what it is, but it looks expensive.

The MX-500 is a very good remote for the price ($85 or so online from licensed dealers like bluedo.com). The MX-700 is a good bit more powerful, but the power does require a bit more work on the front end at the same time that it gives you more options. I tend to lump the 600 and 650 in with the 500 and the 800 and 850 with the 700 (since the only appreciable difference is RF capability), so those comments can apply to the others just as well.

Ok. I would like a user-friendly PC interface (so that rules out the 500), but I don't need it to have RF. All the gear would be line-of-site, so IR would be just fine.

The 700 has IR and PC interface for $160
The 800 has IR/RF and PC interface for $215
The 850 (upgraded 800) is $190
The 950 is $429 (that's too much!)

So I guess I'd either go with the 700 or 850.
Too bad there's not a 750 that would be like the 850 but only have IR (no RF).

The 850 gives you a somewhat easier to use navigation pad and the ability to use RF in the future if the need arises - at only $30 more than the 700, I'd go with it.

I just bought the MX800. All I can say is me and my whole family prefers the MX500. I don't know what they were thinking. The button to turn on the backlight is significantly harder to press, requiring a different hand hold to apply enough pressure. The transport buttons that are used frequently for skipping through DVD chapters and PDR content are missing and replace with something that could easily go into the LCD screen. The play button is moved from over the thumb pad to under where it's harder to reach. In my opinion the MX500 is a much better feeling remote in many ways. On the other hand they did improve the thumb pad operation, they improved the way it handles toggle bits and you can connect it directly to your computer to configure the remote. Some of the reasons that I haven't sent it back.

There was definitely a learning curve when going from the 500 to the 700 - the re-arrangement of the buttons around the navigation pad was a real mind-bender. I moved the chapter/track buttons to the channel up/down keys for everything except the the DVD-R. The DVD-R needs them for the channels, so the track controls are on the LCD (where my wife no longer hits them by accident while fast forwarding through ads). It's worked out well, but those first couple weeks were pretty confusing.

Have you looked at Harmony remotes? My MX is in a drawer somewhere now that my Harmony 880 is here

Harmony also has a good reputation and is worth consideration. Personally, the tweaker in me prefers the flexibility of programming allowed by the Universal MX's.

I have used both, as I tried the Harmony for my brother and sister-in-law and personally I will stick with the MX series. I prefer the look and style of the Harmony but the software is so dumbed down that IMO it makes it counter intuitive to program past a basic level. Maybe if I wasn't so familiar with the almost limitless boundaries of the MX software I would have liked the Harmony better, but as it was it wasn't for me. On a plus side, it was extremely easy to get the remote programmed on a very basic level, but to me the small learning curve on the MX software is well worth it.

I agree, the jump from the 500 to the 700 did take some adjustments, especially that dang play button Now that I have gotten used to it I actually prefer it there. IMO, it makes all kinds of sense to have all of the dvd/vcr action buttons (rw, stop, play, pause, ff) all in sequence in one area under the cursor instead of randomly placed around the cursor.