Both kits are amazingly good for magnetization, so I encourage you to do so.
Re: The Stormwolf vs Stormfang: The Wolf is better, but having the option later on is pretty good. Some tips:
- Magnetize the lascannon/missiles previous to full assembly or they are a bear later.
- Do not glue on the front door, teeth above it or the slidey bit that goes on the long bit. Also, magnetize or dry fit the rear hatch. All of these hold well without glue so will be fine.
- These will allow you to swap to the stormfang in the future. Just put aside all the extra bits for later.
Re: the dreadnought
- I magnetize the hip joint, the hands and the arms. This allows you to fully customize the model later into all the different versions (Murderfang, gun claw/dread and axe/shield dread)
My gallery has pics of the swaps and I can provide more info if needed:
http://www.dakkadakka.com/gallery/images-20774-4758_Pretre%27s%20Space%20Wolves.html