After going back to a paper planner after trying an excel planner, I’m also tempted to go back to a paper mark book, for the simple reason of being able to take it round the class with me. At the moment I print of a list of names write the marks down then I have the task of entering that into the markbook later (or not) as another piece of admin that just bogs me down.
There are other advantages (or disadvantages): I think I’m less likely to forget my book especially if its in the same book as my planner whereas my memory stick lives down at my feet in the machine on the floor (I have made a speciality of forgeting it on Friday night which complicates planning). Back up once a month by photocopying (just slightly more complicated than the stick)
The only thing is my penmanship on such documents is not accurate and mistakes could be costly.