You also need to factor in extra load times using images as opposed to a CSS-initiated background. Although it is important to have anchor text for images on your site, I dont think that you should go out of your way to purposely make the site less usable in exchange for a negligible amount of rank increase. After all, it doesn't matter how well you rank if it doesnt create conversions for you due to slow load times, incompatibilities, etc. I generally like to tell my clients to keep the end-user in mind first, as implementing this type of mindset will usually automatically help you with SEO (quicker load times, better quality content, etc). Just make sure to use alt/anchors for the actual images on your site, and you'll be good. I'd definitely recommend using CSS over hard-coding a bg image. It's better practice, and will decrease load times on all your pages.

That sounds like a great plan. Furthermore, on the high-performance sites that you have the higher CF plan on, you'll also get Railgun. I've had a chance to utilize CF's railgun technology through a partnership with a hosting company, and i can say that its quite effective with even dynamic content (unlike most CDNs). Furthermore, it may decrease your overall technology budget by mitigating the need for a separate CDN. Visit https://www.cloudflare.com/railgun to read more about it.

Good luck!

I've been using Cloudflare for about 2 years now with 10+ sites (including 2-3 that receive 20k+ unique visitors monthly), and to be quite honest I have not found a DNS provider that provides the same level of optimization and security as them. I've tried some of the top companies in the DNS industry (including Dyn, which I still use for enterprise DNS redundancy & fail-over), however they all seem to be missing functionality that I regularly use within Cloudflare, which I ended up moving back within a week. Furthermore, performance-wise, I've yet to find a service that can match site load times accomplished with an optimized CF setup.

It does take some time & experimentation to dial in the optimization/security settings within Cloudflare for your particular site(s)/technology, however once dialed in, everything runs quite well. My favorite features are the DNS-based smart redirects (you can create URL patterns which will automatically redirect pages for you at the DNS-level.) along with their DNS-based firewall. The latter stops malicious attacks at the DNS level (it can cut off the hacker/spammer at the DNS level before it hits your serrver, as long as the user accesses your site using the protected domain), and has been quite effective for us for the past 2 years. Furthermore, Cloudflare reduces load times in various ways (caching at the DNS-level, JS/CSS minified, etc). They also allow you to integrate apps such as Google Analytics without having to directly add the JS code into your site.

In regards to Cloudflare optimization, after implementing the proper settings for one of my clients ecommerce sites, we've seen load times decrease by about 3 seconds on avg. Like I've said, it does take some time to get the optimal settings for your specific site, however I feel that its definitely worth it.

I'd recommend subscribing to CloudFlare Pro ($20/month for first site, and $5 for each one afterwards), as it comes with the WAP firewall at the DNS-level (which works almost TOO well. Sometimes detects actions on the backend as SQL injection due to the query patterns), along with SSL support (really cool, you can have SSL connected at the DNS-level). I believe you also get a LOT more slots for the smart redirects, which is invaluable to me. I know I probably sound like I work for CF, but to be quite honest I've experienced nothing but great service from them. The one time I had an issue, I contacted them on Twitter (which they actively check) and they replied/fixed the issue for me within a few minutes.

Hope this helps you make a more informative decision. Feel free to send me a private message if you have any other specific questions. I'll see what I can do to help out.