Yes, that was the same thing that you suggested at the time, the .htaccess code. But that didn't work, and I just didn't have the time back then to chase it up any further.
The solution in the FAQ really should work (I know of no other way to prevent content modification over a 3G/4G connection) and content modification will have the same effect on Juicebox (and many other websites which rely heavily on JavaScript) so if using 3G/4G really is the source of your problem, then you might need to resolve your problem before going forward with Juicebox. However, if the solution in the FAQ does not work for you, then this suggests that the problem may lie elsewhere (perhaps a Flash related issue).
We have a similar FAQ for Juicebox here:
Why can't I view my gallery on a 3G mobile connection?
If you'd like to switch from SimpleViewer to Juicebox, then I would recommend trying Juicebox-Lite (the free version) first. You can download Juicebox-Lite from the Download Page.
Try creating a Juicebox-Lite galley (check out our Getting Started guide), uploading it to your web server and viewing it over a 3G/4G connection to see how you get on.
If the gallery does not display, then the problem is almost certainly with 3G/4G and you might need to contact your 3G/4G provider and/or web host to see if they can help further.
However, if the gallery does display, then you should have no problem upgrading from Juicebox-Lite to Juicebox-Pro.
Please check your email. I have sent you a message regarding Juicebox-Pro and the discount for SimpleViewer-Pro users.