Dude, when it comes to 1/8 scale buggies and Truggies, you would really want something more then 30C. Maybe where we play doesn't make a big difference, however you will notice the difference at the control end. At the same time, the more C discharge the battery is capable off, the less damage it will sustain or swelling. With the Vorza and the mamba monster ESC, it will demand more power from the battery unless you really tweak it down to the min.
My experience is the below and I will only buy from these two brands:
Maxamp: 4s 120C (http://www.maxamps.com/proddetail.php?prod=Lipo-6500HC-148-Vorza-Pack&cat=218)
Maxamp: 5S 120C (http://www.maxamps.com/proddetail.php?prod=Lipo-5450HC-185-Vorza-Pack&cat=218)
Intellect: 4S 70C(http://stores.ebay.com/RC-MALL/Wire-with-plug-race-pack-/_i.html?_fsub=2274710013)
Maxamps are amazing lipos but damn expensive. I've been using them for more then a year now and I'm guessing more then 30 cycles on them and so far, consistent performance since new. I've been playing with the Intellect and at less then half price, this lipo rocks. Granted it's about 2 month old, so I'm not sure after how many cycles the performance will deteriorate. As of now, very happy with it.
One thing I would recommend with lipos is to always balance charge and never charge immediately after playing. The thing will swell and most likely catch fire