Why would a FHC want to use Internet Explorer?
The main reason is that the Portal assumes that you are using IE. That is sufficient reason!
Why would a FHC not want to use Internet Explorer?
IE has serious compatibility problems that pop up at the most inconvenient times. Sometimes the patron is unable to see a document image. Other times a patron is trying to register for an account and is unable to advance beyond the page with the Captcha security text. If so, the patron will get stuck at the same spot when trying to recover a forgotten user name or reset a password!
Often the IE compatibility problem can be solved by setting the compatibility mode for the website. This is most easily done by looking for the "torn page" icon in the address bar. If the icon's background is gray, click it to turn it blue, and the problem is usually solved.
My personal suggestion is that FHCs should have Internet Explorer, Firefox, and Chrome installed. That way if they run into a problem with one browser the solution is just a click away. The hard disks in most FHCs are nearly empty, and these are relatively small programs. I see no reason not to have them available. Safari is a good option, but probably not necessary if the other three major browsers are installed.
I would avoid installing the free toolbars etc. that are offered during installation of the browser.
I would leave IE as the default browser, as the Portal expects it. Run FF or Chrome as needed.
When patrons wish to register for FS or LDS accounts, use FF (or Chrome) to avoid problems with Captcha. The same is true for recovering user names and resetting passwords, where Captcha can be a roadblock.
It is handy for FS Support if patrons can access their web-based email in the FHC (recover/reset uses email) but that would be subject to local policy.
My personal suggestion would be to use IE if you don't have any problems, and switch to FF or Chrome to deal with the problem, and then return to IE.
As the Family History Department moves everything to the internet over the coming years, the web browser becomes the key to accessing all of these services. For the present at least, I believe that every FHC should have a recent version of the three major web browsers installed on their machines.