Exactly.You picked up on my very point. Trane two stg upper end models are very poor with their performance numbers and BTUs in both cooling and heating.
I suggest looking at the single stg Carrier Performance 15 model and Trane's XL15i paired with matching var speed air handlers. Of course with the Performance model, I would recommend the Infinity Controller and with Trane's XL15i the Honeywell Vision Pro IAQ-simply dislike Trane's stats. The performance numbers on these models are very good.
1258753 Active OEM PERFORMANCE 15 PURON HP CARRIER AIR CONDITIONING 25HPA548A30 FE4ANB006+UI 48000 13.00 15.50 47000 8.70 29400
1382178 Active OEM XL15I WEATHERTRON TRANE 4TWX5048A1 4TEE3F65B1 48000 12.25 15.00 47500 9.00 30200
Numbers provided from the CEE HVAC directory