MK4 to MK4S Upgrade, without New Wi-Fi/ NFC

TLDR;

If I upgrade the MK4 to MK4S without the new electronics (New Wi-Fi board, NFC), Which firmware/printer selection (MK4 or MK4S) should I select?

The reason I'm asking is that I don't need the new Wi-Fi and the NFC. I have an MK4 farm that I want to upgrade to MK4S.

Upgrading all 5 printers will cost $500, also the upgrade takes 1 to 2 weeks to ship. I already have the new CHT nozzles and a roll of PCCF.

I found the 360 metal fan holder and 5020 fan for $20.

So Upgrading all 5 printers will cost me $100 instead of $500.

I'm just curious what are the differences between the MK4 and MK4S in firmware selection?

TLDR;

If I upgrade the MK4 to MK4S without the new electronics (New Wi-Fi board, NFC), Which firmware/printer selection (MK4 or MK4S) should I select?

The reason I'm asking is that I don't need the new Wi-Fi and the NFC. I have an MK4 farm that I want to upgrade to MK4S.

Upgrading all 5 printers will cost $500, also the upgrade takes 1 to 2 weeks to ship. I already have the new CHT nozzles and a roll of PCCF.

I found the 360 metal fan holder and 5020 fan for $20.

So Upgrading all 5 printers will cost me $100 instead of $500.

I'm just curious what are the differences between the MK4 and MK4S in firmware selection?