Victory !!
Ok .. I know this is an older thread, but I was having the same problem on my 2010 15" MBP after upgrading to a Crucial MX 100 512 GB.
Plan A was to recover my user info from a Time Machine backup, which is living on one of the hard drives on my Mac Pro. Both computers are updated to the current version of Yosemite, but when I was looking at the ETA it was something like 67 hours and not getting any better .. I contemplated a Plan B with Firewire in Target Disk mode or something along those lines, but as a last resort, I thought to leave things alone overnight and see how the progress was in the morning .. now it's the morning and the ETA was STILL in the 50+ hour range. I originally had the computers connected via an ethernet cable and had assumed that they would be using that network as it's the fastest connection possible (Both are Gigabit ethernet). To check, I turned on Activity Monitor on the Mac Pro, and switched off the WIFI to confirm that wasn't where the ~1 meg/second was flowing. Then watched as the network Data sent/sec: field dropped to zero. AHA !!
I restarted everything with only the ethernet cable connecting the 2 machines and now the MBP has already caught up to the previous level of completion, but only took 1 hour to get there (vs overnight). So now instead of 50+ hours on the ETA, it's down to about 3 hours, and showing a Data sent/sec: with peaks over 45 megs per second (a few 50's here and there if you watch it long enough).
So .. the moral of the story .. make sure you've forced your machine to use the fastest connection possible, or else you might get a surprise, and miss a week of work as a result while your machine sits there loligaging along vs RIPPING along
(FW max is 400 or 800 mb/s depending on your mac's ports, and Eth is usually up to Gigabit (1000 mb/s) if it's been released since 2010)
Cheers to all !