Regarding the Tanakas, I recently bought a TCG22EASSLP straight shaft string trimmer. It is very light, well balenced and has plenty of power. Don't know about longevity, since I've only had it a few months. They are also offering a rebate that brings the price down to about $150, but the rebate takes forever to get to you.
Are you interested in selling any of the used Redmaxes? I'm local and wouldn't mind taking a look.