As a PC user I find that 7.2.1 or 7.2.2 very stable. Not sure why the Mac side is having so much trouble. I am not using win 8.1 for any production work, however when tethered with the Surface pro 2 or 3, I have C1 open and again very stable.
As for differences between L1 and C1, as user of both on the Nikon files, I can a bit more on areas I find to be strengths or weakness.
1. LR is catalog only, I don't want to be forced into only a Catalog, as I have no desire to have all my images in a catalog, for my style of shooting, it just makes not sense. C1 with it's session and catalog setup is my preference.
2. I find now I rarely use CC for much other than a slight tweak of a file and I do the vast majority of my work in LR or C1 as both have excellent tool sets.
3. C1's implementation of adjustment layers, again a plus since you can turn off each individual layer to see the effects, in LR with the adjustment brush it's currently an all on or all off. This makes is hard to really tweak an individual layer since you can't see only it's effect on a file
4. LR has noise, reduction available in the adjustment brush and the ability to use the WB tool in each adjustment layer. And you can overlap adjustment brush adjustments and each doesn't cancel the other out.
5. C1, usually has a better color adjustment selection that LR. However in Local adjustment layers, if you overlap a layer and try to make a 2nd color adjustment in a layer that is overlapped and which has as color adjustment already, you will get a error and C1 creates a strange blooming effect. This happens in mac and windows and C1 is aware of it, but has told me it is due to the design of C1 and icc profiles in the layers. LR in effect has figured out a way to get around this by allowing you to have WB adjustments in separate adjustment brushes that don't cancel each other out.
6. C1 has a bit better base profile of the D800 camera and at times I will use the Phase One IQ250 profiles on the D800 files. LR has gotten better, but the default profiles are a bit harsh and you really have to be careful. I don't have any custom profiles for the Nikon D800 in either software.
7. C1 to me just has tethering down. I have tethered the D800 several times just testing it and it's very solid. I really don't have a need to tether the D800, but it's nice to know it works. LR I have not tried a tethered session on Nikon.
8. LR HAS A HISTORY, Man, do I wish C1 would read this and figure out how friggin important a history file can be, especially if you do a lot of adjustments on a file. It's great to be able to go back to an image you worked on 6 months ago, open it in LR and you can still see the steps you took. Sure C1 has the undo but if you are working on multiple files which I often do, you will get lost very fast as to where you are. I have mentioned this to C1 10 times at least on beta reviews, and open cases, but they apparently don't deem it important.
9. LR has just a bit of an edge on sharpening with the D800e files, C1 has gotten much better with Vr7 however.
10. Highlight/shadows pretty much a draw, as both tools have gotten much better. LR will allow shadow adjustments in an adjustment brush which is a nice feature.
11. Adjustments for perspective, LR is more user friendly. I have really never been able to figure out the C1 adjustments here, and have tried quite a few times. With the latest version of LR, the "upright" tool is an excellent addition.
These are the main issues differences I seen in daily workflow. I am sure many are unique to my style of working.
Paul