Do you have to clear nvram evertime we upgrade different build number using 1.28.7471MIPSR2-Toastman-RT-Ext.bin
You should, although often you can get away with it particularly if the firmware update is from the same "stable" as your old one. But if anything (anything AT ALL) unusual starts to happen, before you complain to the forums, an NVRAM erase will usually clear the problem.
But reconfiguring is very easy even if you have hundreds of things to configure. Follow this link:
Download site http://www.4shared.com/dir/v1BuINP3/Toastman_Builds.html (inc. torrent downloads)
Make a Paypal Donation http://toastmanfirmware.yolasite.com/donations.php