I am thinking about making a regrade of the new UHD Transfers of LOTR, so they look like the DVDs, in terms of sharpness and definition would it be worth it or should i stick to this version?
I would go with the UHD versions. They are definitely improvements.
But it turns out that many Blu-Ray reviewers have found out that all six movies and the Extended Editions were very likely all the older master files (the sloppy color grading job on the HD version of FOTR Extended excluded) upscaled and regraded one more shot-for-shot with extra digital noise reduction and sharpening. Jackson even admits that the color grading in FOTR was analog compared to the sequels, while he said that the green tint was intentional alongside director of photography Andrew Lesnie to bring it in line with The Hobbit. Also, this video has proven a good point about the 4K UHD releases and the problems within the transfers.