PLUSES: Twin XL is extremely comfy. Sleeping deeply in various positions. No rattle or moving when partner gets up or moves. Xtra functions are a benfit (Raising / lowering head and feet area, massagers, etc.)
MINUSES: The gap between two twin xl's is actually more of a gulf with no way to really close it. It does not feel like a king bed. Bit soft around the edge of the bed when sitting on the edge of the bed.