I use Herpstat, I have 2 once for my racks and the other for my incubator, I just really like herpstat, can't talk about Helix as I don't own any.

the thermostat is going to be used for a incubator
If you are using an herpstat get the regular one for your incubator.

You will not need the ND since ND is for night drop, and this feature is not needed for an incubator.