I have had the Lumin T2 in on trade and spent about 3 weeks with it as an every day DAC and tested it against a bunch of devices including Bricasti. If you were really happy with the T2, I would look at Weiss or Chord as alternatives. Both the Weiss 501/502 and Chord Dave will keep you tonally similar to the the T2. They are a bit different in their presentation but are both super engaging.
the Bricasti M1 SE is amazing but will be a bit warmer than the Lumin. If you aren’t experiencing brightness or glare in your system now, you might find the Lumin a bit warm relatively speaking.
i am not a Lumin dealer and can’t speak about how the X1 compares. I am a Bricasti, Chord and Weiss dealer.