I didn't know this card even existed but basically it acts like a pizza slice but instead of recharging every 24 hours, it recharges every 12 hours. So on first glance, it seems like a good buy. It's also a discontinued card so there's the rare factor to consider as well.
But then, I looked at the price of the energy boosts and they cost a fifth of the price of a Birthday Cake. So maybe the better strategy is to buy 5 more energy boosts instead.
I'm looking at buying more boosts because I am always one short everyday and rely on finding a pizza slice to get that last mission in.
Another option is to run more of the quick missions in order to maximize the chances of getting a pizza slice and they have the added advantage of earning at the top end of their range.