After playing with my new Disto E7400x a little, I must say the differences between it and the Bosch are striking. I haven't taken it caving yet, but I can hardly wait! Here are a few things I noticed right away:
1. When I use the tilt measurement function, the laser stays on! (Unlike my Bosch)
2. The tilt measurement goes all the way up to 90 degrees, instead of stopping at 60.
3. The laser actually has some functionality in daylight. With my Bosch, I had tried measuring some cliffs where I practice rappelling. I always got an error message, even though the bottom I was shooting at was well within the range of the instrument. With the Disto, my only problem was that I was unable to see the laser dot at a long distance. Other than that, I got what appeared to be correct readings.
4. While my Bosch has a max range of 80 meters, my Disto goes up to 120 m.(390 ft.) Now I just need to find a 390' pit to try it out on!
5. The "smart horizontal" function give me the shot length, the tilt, the projected length, and the height difference, all in one shot. As far as I know, my Bosch didn't have any such function. In order to calculate the projected length, I had to carry a laminated sheet with a sampling of projected lengths at various angles. I used this to draw my line plot on my survey sheet with a somewhat correct length. (Cave Compass also has some projected lengths printed on it)
While the price difference is rather large, the features I listed above make the Disto a much better buy for cave survey purposes. Many of the differences are not clearly described in product brochures, and you don't find out until you buy one.
Trogman