I used to have a paid account.
I feel like the only way to use the data is to have a couple of knowns in the niche and compare the data spyfu gives you with what you know and make adjustments from there.
I've found that within a givne area, it tends to be off by similar amounts. So if the real traffic, say, is 2-4x what Spyfu says it is, then that range probably holds up.