D200, and keep using your glass. What do you not like about the 70? The 80 and the 200 are regarded as huge advances past the 70. I much prefer the ergo's of the 200, especially having direct access to the WB, ISO and QUAL settings. I change them frequently, and I don't like having to move command dials around and go into sub menus.
The 300 isn't looking like much of a step-up from the 200, but it would be a huge improvement on the 70. You may find some amazing deals on the 200 in the next couple months.
1999 e46 328i Ti Silver / Black[retired]
2007 e90 335xi Jet Black / Black[retired]
2011 e70 X5 35d Vermillion Red / Cinnamon
2011 e92 M3 LeMans / Fox Red extended