I would definitely go with the foams unless you plan on running rubber tires when you race big races as well. With not having a lot of money for tires (as most of us do not) i run Jaco's and it seems that the most popular combo at our track is double pink/orange in the front and double pinks in the rear. We usually true our tires down to 59 mm but when we go to races we true them to 58mm.
We have some very analitical people that race at our track and we practice on tuesdays , thursdays with races on Fridays and they keep track of everything. One guy kept track and we can get about 875 laps out of a set of Jacos cut down to 59mm.
In layman terms, I can practice about 3 weeks and race 3 club races before I designate a pair of tires as practice tires. Now if we happen to chunk our tires and have to true them down, that takes laps away of course. We will practice on our tires until we see rim (55 to 54 mm) but that is only because of cost. Now this can vary because we mostly run 19turn because our track isn't huge.
I like the foams because of not having to glue them and people will say that it is a pain to true them but if you have an automatic tire truer, i would rather push a button then to have to glue tires. That is my experience but the final decision is going to be up to you and what you have to spend. With 3 kids, believe me there isn't a lot of money in my budget for tires either. lol.
Jaco / Airtronics
Much More / Team Orion
"Drive Hard or Go Home"