Got yesterday the E4 (thanks Dave and Mike for your reviews) and here is my first impression. This is my first TIC ever and I am not a pro so take this with a grain of salt. The unit is larger than I expected, a little bit on the bulky side but not a problem. It feels lighter than I would expect from a rugged product at this size which gives the subjective feeling of a 'rugged look' but again, not a problem, I don't expect to abuse it. It feels nice in the hand and all 5 buttons are easily accessible and have good feel. Screen size is just right though not very visible in sunlight. Shutter feels 'plasticky' and does not turn the camera on or off (would be nice, will also act as a reminder to close the shutter when turning the camera off).
As Dave mentioned, the lens and the screen are not parallel which makes the aiming confusing. Also, the USB port is not in right angle to the camera surface which is strange when you try in insert the charger plug.
As Mike mentioned, some common functionalities requires digging into the menu structure instead of being available with a single click. For me the range lock/unlock is the most common function (when you look around a room, you want to have the same color range) but I found that if you open the lock/unlock function, then with a single click you can switch between the modes, while still see a live IR image (slightly obstructed by the menu). Same goes goes for other top menu controls such as color scheme and image mode, but not for the alignment distance setting which is more painful.
The MSX function (visible edges super imposed over IR image) works very good but obviously not in the dark (no flash, not even when you take a picture).
Image resolution is good enough for my needs and I would not pay 50% more to go to the E5 model. 9fps is also good enough for me, no complain here. One problem with the image is that is very noisy, you see all the time pixel's intensity jumping up and down, like the noise on old analog TVs. I think this happens because of the automatic ranging, for example, if the scale is 19-35C, this is only a small fraction of the dynamic range of the camera. Since internally they scan at 60fps, they do averaging over few frames (or maybe this is already after averaging).
The most annoying thing about this product is the frequent calibration, every 10 seconds or so the image freezes and a 'calibrating' message pops up. It would be nice to have a 'relative' mode where it does not show actual temperatures, just the relative colors. If I scan the room or a product looking for hot spots I don't really care about the absolute temperature.
Overall I am very excited with this product and it is definitely a keeper. For example, we have in our home a room that gets very hot in the summer. With considered several solutions but a quick scan with the E4 suggests that the hit comes mostly through the glass door and not through the external walls or the roof so we will look for a solution in that direction (tinting, awning, etc).
I also found that looking around the house with the camera reveals interesting information. For example, the UPS in the living room is large and hot, that old transformer that hangs on the garage wall is actually live and hot, that the LEDs lights we install are indeed cool, and that the seal on the no-frost fridge is sometimes cold and sometimes hot (must be some defrost cycle).
I also notices that reflection is a general problem with IR imaging. i can see an image of myself on the wall and shiny surfaces looks hotter than they are, but in other cases it is useful to measure the reflected radiation, for example, if the sun hits the floor and is reflected and hits the rest of the room, it is useful to see it directly to solve the root cause.
Again, overall I am very happy with it. Will be interesting if it can be upgraded to full resolution.