I would use heavy!!
I have broken 3rd gear to many times and this last time really bad, I had a lot of noise going 60mph when I put it into 3rd , I had to push clutch in and turn off the car to the side of high way(This is the day after beating the new cadi supercharged). I was far from my destination so after 2 min I tried to drive the car and to my surprise I could. I listen close and no other grinding from broken pieces. I drove 30 min like that, and im sure it was because of the thicker oil making it harder for the broken pices to move around. I may be wrong but about the pieces moving around but i trust heavy. So if your worried about tranny breaking and still want to limp to saftey use heavy. Whats an extra 2 min warm up, hell I warm mine up for minimum 5 min before I drive in cali