Hi lonewolfx, from what you describe MoI should be a good fit for you, but it will probably take some time to get used to the different workflow from poly modeling that you will need to use.

One of the biggest differences is that with NURBS modeling boolean operations are a primary way to do things and not something to avoid as is often the case with poly modeling.

Part of that boolean-oriented workflow means that you will often want to be creating a shape that is initially a larger sort of extended base "stock material" for the piece and then carve away some portions of it with booleans. Often times people coming from a poly modeling background try to draw in every single edge of the final model and then try to build surfaces between those. That can work for some specialized situations but in general you want to have some of the edges of your final model come from booleans and cutting operations and not all drawn in directly yourself.

Check out here for some links to previous discussions with some various tips for people coming from a poly modeling background:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

So re: ironman helmet that will be made up of several different pieces, and you will probably want to create each piece by that general process I described above of trying to build one broad base shape for it to build the main body of the shape and then carve off some pieces with booleans. Can you possibly narrow your question down to just one specific part of the helmet that you want tips to work on rather than asking about the entire helmet which is a pretty big project to try to boil down to an actual answer?

Also Nicolas Verdon has actually done an ironman helmet in MoI before you can see a screenshot of it here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4737.12

and his web site is here if you want to try to contact him to ask for tips about it:
http://www.nicolasverdon.fr/

But if you want to focus more on one specific piece of the helmet, that might make it possible for me to give you a bit more guidance on a strategy for that particular part. That technique of breaking things down into separate parts and then focusing on each different part as a separate problem can also tend to be a good way to tackle a project too. It kind of sounds like you may be trying to do a bit too much all at once and that may be part of the problem with your current approach.

- Michael