It's a little confusing because Opis actually includes MapWriter as part of the Opis mod. Opis is indeed a performance profiling mod, but because it's integrated with MapWriter, you get the map with it. Also, I think Prof. Mobius updated MapWriter when he did the Opis integration. I don't know if the stand-alone MapWriter ever got updated or not.
As to @
Luaithel's thought on maps: MapWriter/Opis never cause crashes for me and I haven't heard about that type of issue before. JourneyMap and Zan's are the two other main ones in FTB packs, but they both allow you to see mobs on the minimap and have better cave mapping. Both make the pack easier than intended.