I need to hear you experts on this matter.

I am currently building my first site in DNN4.3.5 - We're moving from homebrew ASP to DNN. I am running a motorcycle community site. In this site I want to enable the users to enter some information about what ride(s) they have and their experience with riding.
As far as I see it, I have 2 options for building this into the users' profile: Either use the built-in mechanisms or use the Xmod module from dnndev.

What I have done so far is to remove all the property fields in the default DNN profile. Now I want to add a list from where the users can select one or more(!) motorcycles. In addition to that I want them to be able to select a pre-defined field from the list called "other bike" which enable them to enter a motorcycle into a free-text field (in case their bike is not covered in the list). I'm coming out shorthanded if I use the DNN profile options or is there a way to do this?

I need to make sure that I am going the right way about this, so how would you people do this? Would you add a system list to DNN and reference it in DNN? How should I enable them to select multiple bikes? or should I build an 'extended profile' in Xmod instead?

What I really want, is to make sure I go down the right path as this is a crucial design step in the site design. I'm hoping somebody would spill their thoughts on the subject? Should I use the built-in options or go for some proprietary mod (Xmod). How would I create a multi-select list using DNN?