I would like to thank everyone for their input. If any of you care, I ended up getting the Shield. For those of you wondering the difference between the filed/rental version and the standard version, I asked VForce and this is what they told me.
There are 2 differences, aside from price, between the field Shield and the standard Shield.
1 - The field version doesn't have the "standard" padding around the eyes. VForce uses a special foam combination on their masks, but the rental versions of their masks use regular foam.
2 - The field version is not as rigid as their standard goggles.
All the other aspects are exactly the same. Especially the lens, which is the biggest hilight of all VForce goggles.
Thanks everyone for their help and I hope this thread helps out other noobs or anyone looking for a good, cheap mask.