We have also used the DIY frosting and it has lasted for years. We frosted a double french door into a downstairs bedroom, 20 panes of glass involved and a six pane window. Lots of cutting, but it works well, looks great and provides privacy without blocking light.
I hate to think what we would have paid to have it done professionally. Much cheaper to buy a roll and give it a go. If you mess it up, you can take it off and start again.