Originally Posted by
tom tulpe
Not quite, but nearly
.
Since neither DUB not SIN are in the Schengen area, you'll have to clear immigration (twice - leaving the non-schengen airside and going back there), and you'll obviously have to re-clear security on your way back in. It follows from there that you require a passport that allows you to enter Germany without a visa (or a valid Schengen visa).
Otherwise no problem, assuming you're on LH/*Alliance and your luggage has been checked through to SIN.
Thanks Tom Tulpe for the speedy response.
By the way, DUB (Dublin, Ireland) is in Schengen (I know we rejected the Lisbon Treaty in Ireland but I didn't realise we'd been booted out just yet ;-) )
I think I'll go for the longer lay over so. If we can go out and enjoy Mainz for a couple of hours then it's a no brainer as opposed to the hassle of a tight connection. I think I prefer boredom to stress!