First, a picky technical note:
Holonomic is a general term used to describe a system that can be controlled in all of its degrees of freedom
[1]. For robot drivetrains, this implies the ability to move in two dimensions. A swerve drive, mecanum drive (jester drive, airtrax), and omnidrive (kiwi drive) are all examples of holonomic drivetrains. They allow movement in both dimensions.
I'm going to assume that my "holonimic drive" you are referring to mecanum drive.
Second, there are major advantages and disadvantages to both swerve drive and mecanum drive. I'm not trying to be rude, but please don't come to this community to enlist support for your side. Take a look around these forums; you'll see that the relative merits of these drivetrains have been discussed numerous times before.
I know you honestly believe that swerve drive is the right way to go. In terms of field capability, you're probably right. But there are a host of other factors, most notably complexity, weight, and manufacturing time, which all affect the decision. And in the end, those factors are actually more important.
There will be great swerve drive robots this year. But there will also be some great mecanum drive robots, and some great omni drive robots. There will even be some great robots that use the kitbot drive train. An awesome drive train might help, but solid ball handling and hanging capability will determine how you do. Don't let yourself think that your drivetrain choice is going to doom your season.
Feel? The only way to know is to try it. Honestly, I'd be interested to see what happens - 2359 is asking many of the same questions.
Yes. Even if you have wheels with as much traction as any other drive system, you inherently lose between 50% and 71% of your power. Take a look at
this paper for an explanation why.