When you say walking An Teallach, are you committed to a full traverse, or is the primary goal to tick off the two munros? If the latter, you can avoid the ridge completely and still have an enjoyable day up on An Teallach. If committed to the ridge, you can make it as easy or challenging as you like - i, with a friend, did the full traverse (as well as all 7 tops) the weekend before last, and we started from Corrie Hallie up around to Sail Liath and started from there, taking on a few tops and the ridge before the munros. I quite enjoy a bit of scrambling but will admit we did not fancy the buttress ascent head-on, so went around to the left to ascend a Corrag Bhuidhe a little further on. However, after that, the optional scrambling on the pinnacles is really straight forward - barely grade 2 IMO, albeit with a few narrow sections with high levels of exposure.
We saw quite a number of people on the traverse taking the lower bypass paths and those looked like pretty good paths (in the dry at least). There is a bit of a drop off to one side, steeper in some places than others, but as long as you are careful not to trip, it's really just a path walk like any other. That said, I think I'd take my chances on the ridge rather than the path in winter conditions