i have the TDX 12" and i love it, but the sub is really power hungry. i have it running off a diamond D5 600.1 amp (600watts) and it hits pretty hard, but i heard the same sub running off a 1200.1 and that was just sweet. the suspension is really stiff on those subs, thats why i dont think mine hits that hard because its only getting the 600watts (the amp is underrated, but still, 1000+ watts is best i say for that sub).
i personally never heard the IDMAX, but i have never heard anything bad said about it. if you're not going to be running lots of power to the TDX, like 1000+ watts, look else where, because after hearing the 12" off a 1200 watt amp, i started saving so i can upgrade to the 1200.1 D5
2005 Honda Accord EX Sedan
JL Audio Cleansweep, JL Audio ZR650-CSi, JL Audio 12W3v3 in custom stealthbox like enclosure in trunk, JL Audio A6450, Audiocontrol DQXS w/DDC
Sony 32" XBR BRAVIA LCD, Toshiba HD-A1 HD-DVD Player, B&W 704 Floorstanders, Rotel RC-1070 Pre amp, Rotel RB-1070 amplifier (130x2), Rotel RCC-1055 5 Disc Changer, HTPC as music server and PVR, and XBOX 360.