Does having a dynamic landing page, or set of dynamic landing pages, help the quality score or conversion rates?
Since August of 2007, Google has REALLY increased the amount of weight they put into what’s on the landing page for PPC ads. You can see a considerable difference in your average CPC just by having a few mentions of the keyword you’re bidding on.

BUT

I’m not sure how they go about sending their automated bot to check out the landing page. If they go through by using some keywords in the header, then you’re set…but even so I doubt this would last long as Google would catch on that any person that develops a dynamic set of landing pages can then have their entire keyword list integrated into those landing pages.

HOWEVER

It will certainly help with conversion rates as the people landing on the page will always see something dynamic that speaks to what they’re searching for. If you have to pay more to get them there since Google doesn’t deem the landing page as relevant then it still would be worth it.

CONCLUSION

Do the dynamic pages but keep in mind that this might not help lower your CPC…but will increase conversion rates.

Most important. It’s easy to get caught up in developing a huge keyword list to get as much long tail traffic as possible, but it’s truer now than it was a couple years ago that you can have the most impact on your bottom line by simply taking the keywords that have the highest traffic and rigorously testing different ad copy, positioning and most importantly landing pages. If you have a keyword or small group of keywords that drives most of the traffic and converts at a decent rate (let’s say 1%), then making a small change on that page to target it towards those keywords could essentially double your profits just by increasing the conversion rate to 2%.