He said it's cheaper with 2C, but with more automation as the speedmaster it won't take much time to run a 4C job on 2C press.
The Speedmaster is unarguably a more capable press, but as long as the 3304 includes the console option I'm not sure I would agree with that statement. I don't think the Speedmaster is THAT much more automated than the 3304, although I'm not intimately familiar with the automation on Speedmasters so I could be wrong.
On short run lengths there may not be a huge time difference between running 2 passes on a 14x20 versus 1 pass on a 12 x 18 but I suspect that 1 pass on a 12x18 would still be a little faster on most jobs. It's also easier to visually check and confirm your color in 1 pass. When running 2 passes your first pass has to be done strictly by the numbers with a densitometer. That being said it is entirely possible to do it and do it very well. On long run lengths you will obviously find it very difficult to be competitive if you are running the job in 2 passes. And if a lot of your jobs are short run lengths I would also be looking at one of the new digital color boxes. The newest generation of production boxes from Xerox, Canon, Ricoh and Konica-Minolta are all very, very good and require less operator skill than a press.
For what it's worth here are my rule of thumb thoughts. Bear in mind there are a lot of specifics about your situation that haven't been discussed that could completely negate my reasoning.
If your run lengths are mostly short (under 5000 pages or so), then I would look at a digital box.
If your run lengths are longer then:
If your budget can handle it, get a modern 4 or 5 color 14x20. It's the best choice by far.
If your budget can't afford that and great quality is more important than cost competitiveness then I would lean toward a 2 color 14x20.
If cost is the driving factor and you can live with good quality I would look at a 12x18 4 color.