both are great amps. in your sig you say you have the idq 12 d2 is that the only sub you have? because with just one of those your choices for wiring are 4 or 1 ohm. but yet you say "its a idq12 @ 2ohms 500w"
it should do a good job sq wise if i remember right tha's an amp even Eric Stevens pres of ID approved of. it's a solid a/b amp does enough power. if you could up the price more you'd have alot more options. i am worried if you'd ever want to add on you could always use that hifonics for your inside speakers then get a bigger amp for the subs. or you could spend more now and have it to where you can add on more later.
i like the idea of a jl 500/1 it would be perfect for that sub and if you find one on here should fit your budget. also leaves you room to change set up later in the future and not really worry about ohm loads since this amp can be wired at 1.5-4 ohms and still put out 500 watts