iv climbed vihren the peak near todorka in bansko.... but not mussala... however mussala i believe isnt a difficult peak so u should b fine there is a dedicated route i believe and is quite popular
Maljovitza is great, even from Borovez a half day trip to Chakar Voivoda Hut, I think this is the much better view, even you can walk from Mussala down via Chakar Voivoda hut to Borovez.
If you want to see some pics, just from the winter I can post some albums again here.
Sune