My friends and I had a once-in-a-lifetime experience hiking Nyiragongo Volcano in 2012. Innocent was amazing and did an unbelievable job of arranging the trip: from meeting us at the bus station in Gisenyi, to getting us visas to DRC and accompanying us across the border, arranging transport to and from the volcano, paying our park fees, and hiring rangers for the park. The price is very reasonable for everything he provides. I would highly recommend using him and Green Hills Ecotours.
If you are planning to hike Nyiragongo, I would highly recommend getting a bit in shape first as it is a tough hike and you will be very sore for the week after!