Well here I am.
I have to say it's a though choice.
Both decks are comparable quality wise.
So it's in the xtra features you'll have to look.
Both have the 78 RPM button and high torque, very stable platter...
The Omnitronic DD-3250 has a switch to adjust the pitch range to +/- 20% (so ou can choose +/- 10% or 20%), the Gemini only has 10%
The Gemini has a LCD screen with some info about pitch, platter direction etc., but except the looks it's pretty useless if you ask me. It has some pitchbend buttons too, but that's useless too, because for me the only REAL way to pitchbend on a TT is by and (platter) or by pitch slider only.
And at last it has a reverse switch. A feature that many new turntables have these days. If you want this function on Omnitronics you'll have to go a model higher 4220/50. (Their highest one, 5250, has main tempo too).
So basically I'd say : if you want some good workhorse without too much extra's go for the Omnitronic. Do you want some extra features go for the Gemini's.
But again it all depends at which price you can get them (prices differ much with those brands)