Do I need a digital readout ?

Yes. Once you determine a time and temperature that works for the transfers and graphics you apply most often, you want to make sure that you are able to replicate the settings exactly, every time you print.
If you’re using a manual or bell timer, and a dial thermostat, this is not always possible. There is always margin for error with manual timers and temperature dials.
A digital readout lets you control both time and temperature with digital precision. You can set the temperature and time to your desired settings time and time again, with the same, consistent results.