I have lived with my rel t5 for a year. I put the new REL t5i exactly at the same spot as the REL T5. Measurements wise, the REL T5i do not measure like the REL T5. the bell curve response of the REL T5 is now replaced with ruler flat response of the T5i! the FR is literally flat where the REL T5 was a bell curve. T5i roll off without any issue and if I put the xo setting in middle point, I get exactly -6db at 80hz and -10db at 100hz! again the T5 was a mess measuring wise compared to the T5i. Sound: with both subs level matched and xo matched. the T5i is faster, tighter, have much more body then the T5. the T5 sounds floppy, boomy, uncontrolled and slightly disconnected in comparison. the T5i Bass seems literally glued with the speakers. it sometimes feel that the T5 is adding too much bass. Im shocked by the difference. the T5i adds so much musicality, toe tapping or the feeling that you just want to listen to one last track! Bass Pitch differentiation is now perfect even at very low volume. Bass is now fully detailed, deep, controlled and clear. T5i is never overwhelming even when I purposely boost the sub: the sound just get tighter and more bassy, but its not overwhelming or boomy. with the T5, at some point it just sounded overwhelming bassy/flappy and totally wrong. I did not expect such drastic difference, im blown away and shocked how better REL have been able to make their T5i. when I compared the T5 with the REL S serie at the store a couple of years ago, all the improvement of the S serie that I noticed seem to have been transferred to the new Ti series! im now serioulsy considering getting rel TOTL REL G2. I have a SHL5+ coming in, but I wouldnt be surprised if P3ESR with rel t5i may be just as good as my Shl5+. and who knows, maybe if I had totl REL to the P3ESR maybe it can outclass SHL5+? we will see... stay tuned!