Ever since I read the errata on this talent I've wondered if any PC would ever use it. Now it feels more like a talent for enemy psykers the GM can throw at players, not caring how much toughness he burns since it's not important whether he lives or dies.
I would like to make the following suggestion: make it 5 points of toughness that needs to be sacrificed for each extra 1d10 to the power roll, but make the damage temporary instead (which returns at a rate of one point per hour). Limit the ammount of toughness points spent per round to gain extra dices to 10, for 2d10. If you run a less action oriented adventure, maybe change it to 10 points per extra 1d10 and the allowed ammount spent per round to 20. If you think the recovery rate is too fast you could add the following restriction: you regain one characteristic point per hour as long as you do not use any psychic powers.
Considering the number of battles we usually have when we play, and the beatings we take, if I presented this to our group we'd probably use the 5 points per 1d10 version, but I don't know what your sessions are like. Thoughts, objections, inputs anyone?