There's a good guide in No Quarter #24 for assembling the Bastion kit which I made sure to refer to beforehand. Really there's nothing amazing to note except for using regular superglue instead of that nasty plastic-melting bonding agent that a lot of other kits need.
In terms of pinning, there wasn't much needed. Being lighter, the plastics are a lot more resilient to popping apart. However, being neurotic like I am, I decided to pin a couple spots. The dremel makes very quick work of this step so pinning effort is almost zero. The biggest risk is not accidentally drilling all the way through the piece since the plastic is so much softer.
For this kit, there are 3 heads. I thought briefly about magnetizing the heads so that I could swap them out, however that just sounded like way too much work for so little benefit. To that end, I opted to just use the Templar's head, since that's the model I bought the kit for. I think it is nice that they included all 3 heads.
Now it's time to talk about magnets. This was a pretty tricky proposition for me since I'd never magnetized parts of a model before so I knew this was going to be an adventure. I made sure to pick parts from the Crusader and Vanquisher to do first in case I trashed something in the process. Fortunately I already had some magnets left over from previous orders, so I got drill bits that matched the diameter of the magnets. Then I broke out the power drill. Not the dremel. The power drill. Talk about scary! I hand-drilled a pilot hole with my pin-vise drill and then proceeded to use the big drill. It worked out pretty well overall. In a couple situations I had to green-stuff things back together, but for the most part it worked well.
It took me a couple hours of messing around and carefully drilling and assembling, I got magnets into all the places I needed. Everything holds together quite well, especially since the magnets I used were probably more powerful than I really needed. There were a couple of key challenges:
First, the shield was a real pain in the ass to get on there. I ended up pinning paperclips into the hand (since they are ferrous) and then putting 2 magnets on the back of the shield. It sort of works, but the shield doesn't hold in an angle that looks good.
Second, the left arm (that holds the shield) has a tendency to swivel a bit. It's a result of the way the magnets are in place and their polarities.
So, given those two issues, I'm thinking that probably my solution will be to put a pin in to keep the pieces straight with just one end of the pin glued in.
Well, that's the progres so far. Here's a picture of the Templar configuration assembled. Next step will be to add those final stabilizing pins and then get him primed. He's definitely not going to be ready for the Resurgence tournament at my LGS this weekend. Overall I'm fairly happy with how the magnetizing is working out. I'd like the model pieces to fit together a little tighter, but given this was my first attempt at it I can't complain too much. If there are questions out there about the plastic kit in general feel free to post comments and I'll respond.