Recommend Clarion, Polk, or Other 6.5" Speakers?

I have a 93 closed bow ski nautique that definitely needs new speakers - old ones are torn from previous owner. There are a standard 4, 6.5" speakers in the boat.

I bought a new receiver that is a basic clarion model that outputs up to 50W per channel. Now I'm looking for speakers... I'm not looking for anything to shatter the peace on the lake, but would like it to sound very nice for the price range.

I see the local dealer carries Clarion CM1625 speakers. I've read mixed reviews. It appears that at least some on this site have had good success with them and I'm under the belief that these are considered default speakers for Correct Craft. Here is a link to what I'm talking about:
http://www.amazon.com/Clarion-CM1625-6-5-Inch-Coaxial-Speaker/dp/B000A3183K/ref=cm_cr_pr_product_top

Second, I saw a similarly priced Polk Model (DB651) that has some rave reviews as shown here:
http://www.amazon.com/Polk-Audio-6-5-Inch-Coaxial-Speakers/dp/B000P0PF9G/ref=cm_cr_pr_product_top

My question is whether anyone on here knows enough about speakers or has enough experience with these models to point me in a direction or tell me to look elsewhere. Based on the writeups it sounds like both would be good and are rated for marine application.

Any inputs on technical sound quality, reliability, installation, or general look and feel?

I'm very pleased with the Polks. Would suggest a small amp to push the four. Not for for volume, but for clarity.

I'm interested in all these ideas... though I'm trying to avoid putting too much money into this... not really wanting to go the route of an amp, etc. The MM polks are twice the price... on order of $200 for 4 speakers vs $100 (are these the polks you ref: http://www.amazon.com/Polk-Audio-AA2651-6-5-Inch-Speaker/dp/B001C3P6FI/ref=sr_1_3?ie=UTF8&s=electronics&qid=1255993823&sr=8-3).

Since I have a receiver that outputs 50W max, do you think I'd notice the difference in the speakers when you say "turn it up" or are you thinking of turning it up with an amp (ie, LOT more power)?

So far, comments are on the Polk. Does that imply that the clarion are no good? I have to admit, I think the Polk gray looks a little 'sexier' than the clarion standard white. ...but this is about sound more than look.

Driver side is mounted in the comb pad behind the driver seat.

That's helpful.

I did some more research based on these comments. It looks like Clarion is quite entry level and the Polks are for systems that have a bit more power output.

I think I'm going to go with Alpine M600 for the quality for the power level I have (RMS 2-35W). Any thoughts?
http://www.amazon.com/Alpine-Type-S-SPS-M600-speaker-coaxial/dp/tech-data/B000J3G6PG/ref=de_a_smtd

i have the alpines in my '94 and they sound great.

Ah what to do... the guy at Crutchfield says the Polk 651 is too much for a standard receiver and it won't turn on enough at low power. But several positive reviews and your thoughts on here are that it's perfectly fine. With discounts, the Polk is actually $10 cheaper at the moment than the Alpine. I'll have to sleep on this...

Have not had a problem.

Which one you ordered, DB or MM?

I have four of the polks running off a small amp in my barracuda, they sound very nice at moderate volumes

Thank-you kapla-Sebastion. And what do you have in yours?
Head unit
Speakers
Amp
etc.????

And was it there allready or is that were you installed it?Any extra braces or was there a mounting kit?