WW1 German Helmet Expert HELP!

Hello All, Anybody here a WW1 German helmet expert? I have a M18,(Model 1918), it seems to be near mint. Original paint, no damage, has a full liner but the chin strap is missing, stamped "(Bell)L-64", has rubber stamp of "64" on back inside neck shield, size-date-maker rubber stamp on liner band, all 3 liner head pads have maker and date stamped on back side and clearly readable.

My big question is: Is the M18 more valuble than the M16 model?
How much more valuble?
Thanks, Paul.