As a cabinet maker first and foremost, I would not use Sundeala, it is very unstable and needs a lot of support it was originally designed to be bonded to a more stable substrate like plywood. The problem with plywood is quality, most of the plywood that is imported into Ireland is from the far east and is full of voids and is not properly laminated. It can and does de-laminate and collapse when you try to put a screw through it. Even marine ply is not proper marine ply any more.
To use a decent plywood you would have to use Birch ply which is 5 times the cost of normal ply.
When I started to design my first commercial baseboard I tried ply and Birch ply, the Birch ply was brilliant but commercially too expensive and the end cost of the baseboard was too high.
That's why I use MDF, not the crap that you get in B&Q. I use Medite Premier MDF, it is very high quality and is incredibly stable because there is no grain it doesn't suffer from expansion and contraction the other products do.
It's how the baseboard is constructed that's important. I use 15mm for the frame which is a torsion box design with a 9mm top resulting in a very strong but light baseboard. I have been making them for 3 years now without any problems with warping or twisting that you get from ply and softwood frame.
With regard to track pins I don't have a problem getting them in, I use the Peco ones that are more like needles than pins! Sure the odd one bends but on the whole they are fine.
Here's a few pics of some recent baseboards.