That is a nice writeup Mike, just wanted to clarify/comment a few points...
Insteon has a lower cost of entry (much much lower 2 years ago) so it is the option for those who simply can not afford a whole house transition to UPB.
Not really as big deal any more. $15 difference between a Switchlinc and HAI UPB, and I bet that diff gets even smaller in quantity.
UPB has more manufacturers but less variety in their device lineup (No screw in modules, etc.)
Depends on what you mean by variety. Insteon *should* have a ton more devices from many manufacturers as promised, but that has not materialized yet. I believe the only device Smarthome has over UPB is the screw in bulb module. But UPB has true wired inline relays and dimmers, a plug in I/O module, a plug in scheduler/timer module and a plug in pocket programmer. Insteon does not have those. So at this moment in time I don't think that's a fair statement.
UPB switches have a very reserved/conservative look and feel that is elegant (but not as much fun).
Compared to what? It's all just Decora (switchlincs and UPB stuff). Insteon has a light bar vs a single LED, but that is a personal preference. I happen to think the single LED is contemporary looking. With UPB each manufacturers switch has a slightly different feel and look so there is actually more choice there too. And a UPB switch with light bar is still rumored. Don't understand what is 'fun' about Insteon? Now, something like the i-line switches are 'different/cooler' with their curvy paddle.
Many people say UPB LEDs are not bright enough.
I'd like to see the stats on that. The different manufacturers use different LEDs with different colors (actually not a benefit) and some are brighter than others, but I found the HAI too bright. The SAI's are about right, but also a bit bright and the PCS are a bit dimmer. But I think you may be thinking about complaints about the UPB slave switch (UFR). The LED on that is all but worthless, but the regular switches LEDs are plenty bright and I've never seen a single complaint on that.
Most people say it sucks that UPB kaypads do not have LEDs for each button.
That's only for SAI and because they offer many different paddle configurations - which is something else not available on Insteon. I really like ones like the dual vertical paddle which looks just like a regular decora panel, just split in two. Use one for the local load and the other can be used for a scene or to control another load with a wired in module. The HAI and PCS multi button do have lighted buttons that light up individually. Now, there is talk about the light when used with scenes or when there are multiple loads in different states and how to reflect that with 1 light.
Not sure if there is a UPB RF remote?
No, but then again UPB does not do any RF at all. But I can easily use any x10 RF device with the converter, or any other wireless device (like a Caddx keyfob) to control UPB device via a panel or other HA system.
UPB was designed to meet the needs of professional installers (and wealthy DIYers) with a large profit margin and easy setup using UPStart. It was intended mostly to control lighting and set lighting scenes.
I am far from a wealthy DIY'er but I put a big value on my time as well. When I decided 2 years ago, UPB was (and still is the leader) much easier to setup and program, and I did not have to battle defective paddles, although in all fairness there was apparently 1 bad batch of switches from SAI which I did have to swap under warranty (with no questions or issues I may add). Yes, Insteon will leave more cash in your pocket, but its not a huge difference any more when you factor in everything.
The marketing strategy for Insteon continues to defy any logical analysis. It is clear though that Insteon is meant to control a much broader range of devices including thermostats, low voltage relays etc. It is becoming common now to assign a button on an Insteon controller to control a garage door for example, or have the light on a spare keypad button act as an indicator for something. Great hobby stuff that might not even interest a UPB person.
I can pretty much do anything with UPB that you can with Insteon. Insteon *should* have more integrated devices as hyped, but its not there yet. UPB has its own low voltage relay (I/O) module and I can track light status with lighted keypads. There are also UPB controlled t-stats, pool controllers and even vacuums.
I don't want this coming off as a 'defense' or pro UPB post, just want it all balanced with right info. They are both excellent protocols and have their strengths and weaknesses. And each will appeal to different people for different reasons, some which may seem trivial. Some people may just be 100% about cost, regardless of how big or small a difference - they will go to Insteon. Some just have to have light bars, they will go to Insteon. Some just have to have configurable faceplates - they will go to UPB. Some will try the feel of all of them and pick based on what feels right. Some want pure easy of programming, they will go UPB/ with UPStart. So I stand by my original recommendation to just try them both and choose based on their wants/needs - either one will work well and come with their own issues.