My newest laser is a TopCon RL100-2s. It's a programmable dual slope laser. I decided to buy this unit (in the $3-4k range) because I felt that I wanted to buy a better quality laser than the ones I had purchased in the past. I have had the laser for several seasons (this will be my 4th or 5th). I am not sure that I would recommend this level to others. I have had some problems with it. More than I would think is acceptable for a high quality instrument. Often, usually when cold, it will give me an E-83 error code. I have returned, it several times, to my supplier. While they have been great by giving me a loaner, they have not been able to find out why it is doing this. Even TopCon has been involved (the laser even went to them) and they have not been able to figure it out either. Ultimately they gave me a new one. While I do feel as though this is great, I have had the same issue with the new one (all the loners too). Of course, I am the only person who has ever had this isssue, according to my supplier and TopCon. It must be due to my specific environmental conditions and/or the way I treat it.
One of the features that I like is that it comes with rechargeable batteries. They seem to last a long time, can run the instrument if plugged in to a receptacle (while charging), and the unit can be run on D cells in a pinch. I read one post where someone was complaining about sensitivity in the "transmitter upset" feature. While this is certainly a PITA it is much better than grading the job to the wrong grade if the laser is bumped. On my TopCon this can be turned off.
Prior to that unit I have purchased a much less expensive laser. I started out with a CST LMH400. It is also a programmable dual slope laser. I'm pretty sure it's made in China. After about 3 years it would fail, about once every year, and require service. That's hard to complain too much about as any laser should receive anual callibration anyway. This laser lasted about 8 years before I was told by the repair shop that it was no longer worth repairing. While I still had the CST I purchased a David White as a second level. I don't recall the model number but it is the same unit as the CST with a different cover. It has proven to be a little less trouble than the CST but does seem to consume batteries faster. It also has proven to be less troublesome than the TopCon, and will usually work when the TopCon refuses (extreme cold). Same job, same day, same time. So far the David White is still going strong. It resides in the crew truck and is used almost daily. If memory serves, the CST cost me about $1,700 (bought new in 2001 from White Cap) and the David White was about $2,000 (I think I bought it in '05). Both included a story pole, case, tripod, and receiver with the transmitter. The David White also included a hand-held remote. Both run on D cell batteries.
I would like to clarify something about the dual slope lasers that I have seen. Lumberjack had stated that he wanted to do a parking lot that drained to a swale (esentially creating a valley as I understood it). I am not aware of any laser that can broadcast (2) grades along the same axis. This is what would be required to make a "V" unless you set and graded one side of the valley at a time. As with any laser it has (2) axis..."X" and "Y". The (2) axis are set 90 degrees from one another. If one wants to set both axis on a slope this can be done but it is essentially the same as making a table top that is pitched forward, and to the right (as an example).
Another thing to note is that if you are using the slope feature, for pipe or grading, the laser MUST have the sloped axis parrallel to the intended slope. If one works along a radius, or has a curve in the pipe tie, the slope becomes in-accurate. The farther away from parrallel, the less steep the slope will be. Working a radius can be done but it requires frequent reseting of the laser and is still not accurate unless the radius is composed of a bunch of short straight sections that deflect where they intersect.
I hope that this makes sense to the reader.