I'd love to have both again to renew my impressions - but sadly sold the 250s quyite a while ago now. I knew I should have taken more notes when I compared the two . Apart from the differences I've already mentioned - they were far more similar than different. IMO the 880 family loves tubes though (or more correctly - I love a tube set-up with my DT880s). I had a Porta-tube amp at one stage - and it was sensational with the 250ohm DT880s.
Over my solid stage (NFB-12) the LD presents a touch more bass impact and definitely brings the mids forward - this is with my 600 ohm.