The following information compares each of these Mice. The 3500 model, although it is not as feature rich as the 4000 model seems to be better for the following reasons.
1. The 3500 model is slightly smaller in size and better suited to children's hand size.
2. The range is greater for some reason. More than 15 metres. I don't understand why as both should be built to the same specs and use the same frequency and receiver. The 4000 model was erratic at ten metres. This may just be an anomally as I have only tested one of each.
3. The button configuration is perfect for Mouse Mischief. The 3500 model has distinct and audible clicks. The scroll wheel is also distinctly clickable. The 4000 model is almost silent when clicking. The scroll wheel also rolls smoothly. There is no distingishable click when scrolling. Also, it is capable of horizontal scrolling as it is also a tilt wheel. This feature isn't necessary for Mouse Mischief. It also has a side button which is configurable. I will disable this button using the sofware provided as students don't need this feature either and it could cause problems with other applications.
The tracking capabilities of both are excellent. They use BlueTrack technology which means they can work more reliably even on uneven surfaces. Same type of tracking that my MousePen uses and that 1st ellusive mouse I bought that I can't get any more!
The battery life of each is also excellent. The 3500 model claims 8 months and the 4000 model claims 10 months!! They also have an on/off switch which is essential.
In fact, the 3500 model is virtually THE mouse that I have been searching for, since I began working on this project over one year ago. (See blog post below for other suitable mice that I have purchased.) All the specs are exactly as I described months ago for the perfect mouse. Its size, button configuration, blueray tracking, frequency and range, on/off switch and battery life all make this the better mouse for this project. It is also quite robust and sturdily built. It is almost as if this mouse has been developed based on what I desired the perfect mouse should be over a year ago. It is also much better quality than the other mice I have purchased. These other mice were about AUS$11 each delivered. I did experience some issues with them and the suppliers though. They still work well but as the saying goes, "You get what you pay for."
The major advantage of the 4000 model is the fact that when clicking the buttons it is virtually silent. When there are 25 mice all clicking at the same time it can become a little annoying. I would love to get student feedback on their preferences.
Finally, if it come down to cost (and this is meant to be an affordable SRS) the 3500 model I believe is cheaper by about $10 each. Please correct me if I am wrong. Either mice would work perfectly (I just want to make more tests with the range of the 4000 model). They are great mice. I wish I had come across them last year.
Again, thank you so much Mj. They will be put to great use. It appears that there may be some very exciting opportunities for me on my return to work. I can't wait."