I was surprised to see that your Burley doesn't come with a shock post, and looking at the Burley site, none of their road tandems do, except as an option. I just checked around the web and found that Trek, Cannondale, and Co-Motion, for example, all come with a shock post.
When we tried a Trek T-2000 (with a shock post), my wife thought the ride was rougher than she wanted...we ended up with a used Burley Softride.
Would most stokers on aluminum tandems want a shock post for basic comfort?