RE: which engine?????
I wouldn't get either. I had the Alpha .24, and found it overpriced for what it is. Lots of people love VSPEC's, but I am wary. I have seen several die early deaths at races. They had a very bad reputation for having bad conrods..
If you're on a budget, I would highly recommend an Argus A52 with 0801 pipe. GREAT value-for-money. I'm currently breaking one in now, and I really like it. It has a lot of pinch, so you have to preheat it before starting during break-in, but it runs great once warm, and is very easy to tune. With the 0801 it has great power too, AND good run times..
I would also take a Werks B5 for ex. with 2013 or 2058 pipe over your two choices.
Argus A52, Alpha A852 or S852, Go GXII, Werks B5.. Those are the ones I'd be looking at for truggy. Oh yeah, the Alpha .23 would be way up high on my list too..