polk vs alpine subs

I have been trying to figure out a better subwoofer configuration.

I have a pa1200.1 mono amp. http://www.sonicelectronix.com/item_...PA-1200.1.html

it is driving two Polk Audio db1240's in a sealed box http://www.crutchfield.com/p_107DB12...40.html?tp=111

I was thinking about switching to an alpine type R (swr 12d2) with the coils in parallel so I could supply 1000W RMS at 1 ohm

http://www.crutchfield.com/p_500SWR1..._12d2&skipvs=T

The goal is to save some space in the passenger storage. Would anybody be able to inform me of the change in sound between these two configurations? Will the single alpine sound more powerful than the 2 polks?

Connor,
The Polk subs referenced are definitely entry-level, but very good as compared to typical entry-level products. The Alpine sub is a clear upgrade. Keep this in mind. Subwoofer surface area is more effective in creating acoustic output than more amplifier power or more subwoofer excursion. So in terms of pure output, two 12" subs hold the advantage over a single 12" sub. Subwoofer power handling ratings do not necessarily correspond to higher output levels.
I'm not entirely comfortable with many amplifiers running into a 1-ohm load even though they may be rated for 1-ohm operation.
IMO, it's not an automatic upgrade. Maybe you can keep searching for another approach. I would start with the maximum enclosure size that you can tolerate.

hmmm. i have an old 600w alpine PDX-1.600M amp @ 2ohm into a polk dual voice coil 12 inch sub and it is more bass then anyone would ever want...it is in a sealed box pictured. the sound and tone is perfect. pay more if you want a different name on the amp or sub. but the right box, and power ratings will provide all the sound needed. i would add that tuning properties of the headunit can make a big difference also. and my head unit allows for a lot of tweaking.