Sorry for not posting more, I have recently had a pile of work to complete, but now that's over and done with, so time for more!
Sort of like a poor man's assault marine, stormboyz strike hard, strike fast, and then die. At 12 points per model, they aren't cheap. They do have the potential for a first turn assault, but there is a 1/6 chance of that. You can still get the shock and awe effect from including boss Zagstruk, but that means that your rather expensive unit suddenly becomes a death unit, and Zagstruk himself is 85 points, which is way to expensive for my pocket!
On the tabletop: The most commonly used method I have seen for this unit is to include Zagstruk , and then suicide on top of a manticore, or some other scary anti-infantry tank, but that inevitably means that your 150+ point unit is being wasted on a tank that is not nearly that expensive.
No, what I see is, don't take Zagstruk, and just take a unit of 10 oth them nilla, and use the opportunistically. See that little devastator squad parked in the enemy's backfield? Use a well-timed Waagh!, a lucky roll for extra move, and you can kill that unit, and then, if you choose to include a nob with a powerklaw, you can take out that Manticore, and hopefully not die.
These guys are no less deadly than they ever have been, but, sadly, have been rendered superfluous due to the new Deffkoptas. Even so, there are some things that Warbuggies can do that Deffkoptas cannot. For one, they can be upgraded to Skorchas, which, as everyone knows, are good, because orks having to roll to hit= points not being earned back.
On the tabletop: You are going to want to upgrade them to Skorchas, no question. Not even the mighty Deffkopta can take the dreaded Skorcha. I would say, a unit of 3 Skorchas should be sufficient for burning non-marines out of cover.
Warbikers (giant pics, ftw)
One of the better options in the Ork codex. Though not as durable or hard-hitting as nob bikers, they are probably a better option for 1500 and under point games, as they are about half the price of a biker nob.
On the tabletop: A cheap, fast-moving, hard-hitting unit is always great, but with a 4+ cover save at all times? Invaluable. Use them as your spear point, to slam into the enemy line before all others. And, remember, you can have an army of them if you take Wazdakka!
Definitely on of the best units in the Ork codex, Deffkoptas bring the firepower where you need it most, quickly and efficiently. Being jetbikes, they can completely ignore terrain for purposes of movement. Add this to the fact that they come with twin-linked big shootas, and are only 35 points base, you can see why they are so popular.
On the Tabletop: Deffkoptas are the most mobile unit in the ork codex, and they are also very useful. If I were playing them, I would take a unit of 3 of them with twin-linked shootas and buzzsaws. That way, though they are very expensive, they can also take on tanks and armored infantry.