I think these guys are talking about cut-a-ways without a 3rd chute....just 'cause you have to get them re-packed to keep them current with the 120-days.
It's seems a little risky, I'd talk to your instructor. PD will sometimes let you demo a reserve that you can pack as a main, that way you know how a reserve ride would feel despite the fact you're still throwing it out.....it'd be worth a try!