RE SRX12D2 or the Memphis M-Class12S4

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I recently removed my old system consisting of 2 Treo engineering 12 tsi running off of an Eclipse mono 500 rms amp and a Zapco i450 running 50rms to my highs with an eclipse head unit and scosche 5x7 highs from my '94 Crown Victoria. I am currently building a new system for a '96 Grand Marquis. So far I have a clarion cz500 head unit, 2 clarion srg5721 5x7 up front 2 clarion srg6921 6x9 in the back a pair of clarion srq211h tweeters on my dash. My amplifier is a Zapco i-5100 seven channel. The amp is powered by 0 gauge wire and with a DC Power OEM 185 amp alternator. I will be running 600 rms at 2 ohm to the subs. Which has better sound quality and output? The 2 RE SRX 12 D2 in an Atrend 1.6 ft3 per sub 3.2 total common chamber vented or 2 Memphis Audio M-class single 4 ohms in the Memphis common chamber box. I am a fan of smaller companies but do not have an RE dealer nearby so I can not judge the RE's for myself. Thank you for all suggestions.