As you may know, the TFD was replaced by the 3DS and as far as I can tell is the same board. I have a 04' TFD 142 with .8 P-wing fins. It came with 1.1 A-wing fins which I put on family member's Motives.
My TFD with .8 P-wings feels really loose and I'm still getting used to it. I am getting more air though and I'm sure it's because I now have to edge correctly with the smaller, looser fins.
ive rode it finless, and wasnt too much of a fan of it. I ride the parks finless and the roam, so i love loose boards. The problem i found with it was it was still a little catchy with the channels (more so than the parks, not saying much), and when set on edge, didnt hold as well as either of them. The reason for not holding as well on edge is that the parks and roam are made to sit deeper in the water on edge than the 3ds. It is possible, but hard to get used to. I would try it, you may like it.
riding the 3ds finless can be done, and it is sweet. The thing is you need to be able to control the board on edge. The difference between the 3DS finless and other boards is the size of the molded fins. I love the feel of finless, but if your not awesome with control on the edge it will make your life miserable. My advice learn to ride a tight board .... harder edge means bigger air and when it all comes down to it amplitude is all that matters