i have a copule of dainese suits i used for the road bike, ( scruitineering you needed to show you back protector ) i always used it trail riding and now its second nature on the VMX/flat track racing.
They are easy to use as your in them, kidney belts, back and armsgurds etc, you dont need to spend 10 minutes finding all the bits before you race like you will with the seperate armour.
Only downside is the mesh seems to need redarning every now and then as you can pull it or rip it. But the mesh is very breathable and never get hot, although i ware a t-shirt under it then the armour then a MX jersy and it seems to be the right mix for comfort and practicality.
the only thing i would say against them is they dont have a collor bone protector, wareas the plastic ones seem to be sit higher and give them the cover over that bone.
Although on the plus the lobster spine and kidney support is what you should be looking at as the single most benifit, you take a hit on your lower back ( not covered in a cage)and your MX carrier is over. GO the Suit evertime !
if your looking to save some bucks i have a spare suit here, smells like sweat and might need to be darned on the cuffs some, but would be half the price of the new one , especially if you just want to see if they are the go for you and your riding style, but im sure you will be plesantly suprised and have no going back ! can post up pics if your interested