Since chasidus is, yechi agrees, toras hanistar manifested in avodas Hashem, many would hold that you’re not mekayam talmud torah with it, the same as by mussar. This would apply heavily to the last half of the tanya, known as the “polisher perakim” because gerrer and others avoided the conceptual first half, and focused on the latter, which was more avodah centered.
If that’s so, it shouldn’t be something you spend 3 hours on everyday. If you hold that it’s a limud of torahs hanistar leshem limud, then it’s a different story, because then it would have the halachik equivalent of learning kabalah – which only counts as talmud torah if you’re holding by really being masig what it is. Something almost no one today can do; you need a high level of kedushah, a rebbe muvhak, and you need to “see” things in it, like the zohar famously changes from the gemara’s “tah shma” to “tah chazi”
Chasidim often said that they’re not learning kabalah in the sense of kisvei ari and limud lishem limud, to avoid this issue; they said they’re learning it because our generations need the fire of nistar to wake us up for avodas Hashem, and I couldn’t agree more – but that makes it a form of mussar, and not talmud torah.