I'm looking for a used 2.5" or mSata Samsung 830, 840 Pro or 850 Pro/Evo. 256 or 512gb of these. I'm not interested in the "usual" 840 or 840 Evo due to the problems which those have. Other quality ssd units which are equal to 830 or 840 Pro in terms of reliability and performance might be of interest as well. Only MLC and SLC are of interest.