So here we are, over a year later, and still looking for the same thing. It baffles the mind that all the pieces are there to make the perfect HTPC remote, and not 1 company has successfully implemented them. I figured I'd review the ones I've used since this thread began and offer my input.
Lenovo N5902 Keyboard/Mouse combo
If you're ok with having a separate remote for tv viewing and one for keyboard/mouse input, the N5902 is by far the best option I've tested. After having my order cancelled initially, they finally started carrying it and I'm relatively impressed. Lenovo made it a point to address some of the gripes with the original N5901's design, adding a backlight to the keyboard and changing the round trackball to an optical one that can be depressed to left-click (feels like a Blackberry optical trackball). Although the range is just ok (sometimes key presses don't register), the mouse control is much more precise than the ball, trackpad or d-pad options I've used. The touch sensitive scroll area is also pretty handy. My only issue with this remote is that it won't work alone. You'll still want something to control your PC eyes-off, single handedly and that can control certain aspects of your TV (like power or volume). This thing only functions as a mouse/keyboard, but it does it well.
Rii I13 wireless HTPC remote/mouse/keyboard
This was a recent purchase. Aside from the frustrating exclusion of a backlight (seriously??), it seemed to check all the right boxes. It includes a gyroscopic mouse (which controls the mouse cursor much like a Wii-mote), a QWERTY keyboard, and a learning (yay) remote on the other side. I purchased a white model to compensate for the lack of a backlight, since I figured it would be easier to see. It also works as a speaker/mic, but don't get too excited. Here are my impressions:
Keyboard - It does the job. You won't be typing a document with it, but it works well enough for entering web addresses and quick searches. That's all you can expect from a device like this, and this aspect of the remote won't disappoint.
Mouse - It has 3 drift/speed settings. Anything above "low" is too erratic to control with any respectable degree of precision, but the lowest setting works fine. I would have preferred the precise control of an optical trackpad, but this thing is usable.
Remote - Here's where it gets a bit disappointing. I was looking forward to the remote's learning functions, but it's cheaply made and has a few operational headaches. The entire remote side of the device needs to be programmed key-by-key, and operates solely on IR. This means you'll need an IR receiver for your PC and will have to spend a few minutes programming each button on the remote's face. I didn't mind programming the buttons (since I could also assign certain ones to control different devices, like volume for my receiver, power for my TV and the rest to my PC). However, the remote is a bit flaky, particularly the directional arrows. Pressing up or down to fast in succession will register as if you pressed the button 20 times, flying through pages in the guide far too quickly. It's also heavily reliant on direct line-of-sight, so pointing it right at the receiver will be necessary. The button layout could be better, but it's workable.
Integrated speaker/microphone - This is perhaps the only truly disappointing feature in this remote. I don't need it, so how craptastic it is will have no effect on my opinion of the remote. However, if you are interested in this feature, look elsewhere. The sound coming out of the remote is not only tiny, but reminiscent of the white noise you hear when a ghost is trying to communicate with you through an electronic device. You won't understand anything coming out of the speaker. As far as the mic, I haven't tested it. The speaker sound quality was enough to get me to overlook the remote's audio features entirely.
The Unicorn - Logitech Harmony 800 QWERTY
This remote seems absolutely perfect, if it weren't for the problem that it doesn't seem to exist. It has a slide-out qwerty keyboard, a full learning IR remote, and a touchscreen that can double as a trackpad. It's also backlit (!). The only problem it has is that it was announced over a year ago and has not come to fruition. Instead, Logitech released the useless Harmony Touch remote. I've signed up with several sites that claim to have this on backorder, but none of them actually deliver. If anyone hears of a seller that can deliver this remote, please let me know.