The
E-book Reader Matrix includes a row for PDF Capabilites. These are not always known, but there is little doubt that PocketBook has the best PDF support. The only downside to the 902/903 is that they have the last generation Vizplex screen (vs the Pearl screen on the KDX). Visplex was certainly considered "good enough" before Pearl came out, but a high end reading device with a 2nd class screen is something to be aware of before buying.
See
PocketBook 602 PDF Review. The 602 is a 6" Reader, but the software is the same on the 902/903. The eBook Reader site also has a Kindle DX review. The problem with the KDX is not an inability to display PDFs, but rather a lack of basic features like table of contents support.
By the way, the kind of PDFs you describe are not good candidates for conversion to a reflowable format (MOBI for the KDX or ePub for the PocketBooks). So native PDF support is what you need.