Those two cartridges are very different. I believe the Transfiguration Proteus to be the more natural sounding. The Lyra Titan i is very revealing and articulate, but may sound thin in your system.
If your system was a bit on the warm side, and you were looking for some more speed and resolution, I would recommend the Lyra, but as you state that you would prefer not to add or subtract from your current very natural sound, I would recommend the Transfiguration.
If your system was a bit on the warm side, and you were looking for some more speed and resolution, I would recommend the Lyra, but as you state that you would prefer not to add or subtract from your current very natural sound, I would recommend the Transfiguration.