I'll be using the saw for cutting expansion joints in concrete and doing some light concrete demo. My dad had Stihl TS350s for years and loved them. I've been looking at a used TS400 (http://orlando.craigslist.org/tls/1077424896.html) and I'm pretty sure I priced a new TS410 at $859. I feel like these saws will do the job, but should I go bigger? Do I need to go with the 410 over the 400? Also, what will I expect to pay for a decent diamond blade?