Having owned both I would say they are both fantastic sub lines. The R's are more budget, easy to get loud, and sound pretty damn good. The X's sound ALOT cleaner but are less efficient. The bass the x's reproduce is extremely deep in an appropriate enclosure and is all in all a unique sound. If you want really impressive bass I would buy more than 1 type X to give you that extra SPL.

Burning smell? Yah I got that too with a pdx 1000...problem: tuned too high = little excursion and alot of power, it doesnt get to breath. As stated before it was a factory made box which are almost always tuned way to high, giving added spl to buyers. The high tuning makes it hard to place a highpass on the ported box to prevent bottoming out. I built the proper enclosure out of fiberglass and I ran a pdx 1000 on each coil without the burning smell.

Blowing fuses? = bottoming out or too much distortion. Make sure the subsonic is on. This IS NOT AN SPL SUB! If you try and make it one by driving it too much the sub will short (to protect itself) and you blow your amp fuses. Took a while to figure this out...about 2 packs of 25 fuses.

Type R's = Good price, loud, clean, deep, reasonable power handling, small enclosure.
Type X = SQ #1, expensive to power, very deep, small enclosure, takes ALOT of power, unique sound. Need multiple woofers for SPL BUT! You just gotta hear them in numbers. I got a sealed 10 (cut off the port, hey I had to try the ported box) and a sealed 12 ...Phenomenal bass reproduction!

Since, most people prefer cheap SPL to expensive SQ, i would say your gonna buy a Type R :) Mass market usually prefers quantity to quality. If not, then why buy the R? hehe

BTW: It's pretty much pointless to build for spl anymore...what with the installs of 6 subs at a time and ridiculously extreme db levels (130+db?, the human ear bleeds at 125 db. Why compete? Save your ears and enjoy the music itself. It's YOUR stereo, why does everybody else have to hear it? Not to mention the rattling...just strap some vibrators to the steel and voila! Same thing. Awwww what am I saying?! An opinion?! Not another one of those damn things...#%!& it! Buy a pair of R's and enjoy the pound! Great sub.

i hit ~138 DB with two new Alpine Type R's in a ported enclosure powered by 1200W's, used it for daily driver and never had ears bleed...
rattling? get sounddeadner of expendable foam and fill thouse. its all fixable

but i agree that for average person type R's will do best
go on ebay and get 2 -> 250$ shipped


but again if you buy used you can get a great deal.
my roommate is currently selling his type x's with a crazy amp
http://www.revscene.net/forums/showthread.php?s=&threadid=505820

I was listening to some house music last week at very loud volume(60/80 on my Eclipse). It registered at 127.4 with my one sub. I guess I could have pushed it more for sake of db numbers, but it was rediculous loud already. Not sure if anyone needs higher volume unless competing in SPL.

There won't actually be blood dripping out your ears lol. It's an internal bleeding. I did a fair bit of research on hearing in my anatomy course and on the internet. Even went and talked to an audiologist and got a hearing test.
The bad thing about hearing is that it's sensitive and anything over like 85 dB is ear damaging...for alot of speakers thats only 1 watt. Kind of scary when you think about it. When i say sensitive, this changes throughout our hearing range. Low end bass needs to be ALOT louder to hear it as if it were the same volume as mid frequencies. Makes a flat EQ not so flat anymore. A quick search on "Fletcher Munson Curve" on google will show you some of the limits of human hearing.

I've had good experience with the type R's, i am currently running 2 12's. They will get plenty loud with a well designed box. I am not sure of what numbers i am hitting, but i can feel an air being moved while i listen to tunes (at close to 3/4 volume of course). If you decide you want something louder, you can always play with box designs..