I currently have a 150ps manual Beach. I recently owned an SE 180ps DSG 4motion. They are both fantastic vehicles to own however if it were my choice I would definately go for the demo DSG for the following reasons:
1. The California with DSG is so nice to drive and it really suits the relaxed free spirited leisure vehicle nature of the California so well. The DSG is a very smooth and relaxing drive whereas the manual involves having to do a bit of work. That's not to say that the 6 speed manual box is a bad choice, it isn't. The manual box is very slick and a pleasure to drive. It might also prove to be more reliable and cheaper to run than the DSG but why have a manual box if you can just sit back and enjoy the drive.
2. The 4 motion is a heavy vehicle (the heaviest in the range), which means that it does feel well planted on the road but that extra weight does cut down the available pay load considerably. The 4 motion system will also add to servicing costs and adds another complication to the vehicle which might possibly come back to bight you later on. In the nearly two years that we owned ours we didn't once find ourselves in a position where we actually needed 4 motion.
3. Out of the three choices, the demo DSG probably represents the best value for money.
As has already been mentioned you should be able to get around 15% discount on an ex demo but only single figures on a new vehicle. The mileage on an up to 3 month old ex demo should only be a few hundred miles at most otherwise its second hand and should therefore be even cheaper still. Yes, you have to accept the spec that the dealer has ordered but if thats OK with you, you should get a bargain. The vehicle should be as new when collected and you should be able to get the extended warrantee and service package as well if you want it.
4. Judging from the survey that has previously been run on this forum the DSG Cali appears to be the most popular choice so should be a more attractive proposition for potential buyers come resale time.
5. Swiveling the front drivers seat on a Cali involves letting the handbrake off. With DSG the vehicle shouldn't move much when placed in Park. With a manual gear box you'll have to chock the wheels and select a gear opposite to the likely direction of travel to stop the van rolling down any gradient, all a bit of a PITA.