Legit just saw your post.. apologies for the late reply..
In regards to your questions aforementioned:
1. My room is about 400sq feet ;
2. 1.5hp x 2 units (as mentioned in my post, a 1.5hp x-deluxe and a 1.5hp x- premium.. i do have a door partition between my “living room” area of my bedroom and my actual “bed area”.. soo at one time, i only turn on 1 a.c. based on room occupancy..;
3. My usage for Hot season i.e. March till July is about 82kwh/month ( for my bed area unit) and about 20 kwh for my living area)… my preference temp is 26 degrees on high fan with auto swing)… take note that on average the unit is powered on for 7 hrs in my bed area and around 2 hrs for my living room area daily.. during rainy season, i sometimes do not turn on the a.c. Case in point: since 20/8, i’ve mostly used my ceiling fan as my room temp hovers around 26 degrees at night and around 24 in the early morning.. KK has been raining extensively lately ( i live next to a forest area and with the rainy season, u could really feel the fresh crisp air billowing through the windows which btw have mosquito netting

)
Short answer: outstanding energy savings.. just ensure that your set temp is achievable and your a.c. Is at the right size / oversize.. never ever undersize, then you’ll see the savings

4. I am not really good at suggesting… however, just get yourself a 2.0hp inverter unit, it can easily match / exceed your cooling requirements.. you may never know when you need the extra oomph.. and with inverter, it’ll continually adjust the speed of the compressor to match your set temperature.. you’ll never go wrong with inverter ( unless it breaks down, so choose wisely).. I’ll always go with Panasonic or Daikin since both are manufactured in Malaysia, hence an abundance of parts and top notch after sales (based on my own experience)… for Panasonic, hands down x-premium inverter if you have the budget or to save cost, x-deluxe inverter ( the 2.0 hp model even has a left right swing compared to the 1.0 n 1.5hp models)… for Daikin, Smarto series hands down as its the only one with a streamer technology ( equivalent to Nanoe-x) and has an added PM 2.5 filter built it… but its costly vis a vis with Panasonic, you’re not getting that “bang for your buck” purchase.. Gree is another option (my sister installed a 2.0hp Queen series inverter) and it does its job well.. except the indoor unit is quite noisy (at medium to high fan speed) and the remote is mehh, the wifi function only turns the a.c. On/off, nothing fancy unlike Panasonic’s iteration.. the outdoor unit is silent though, I’ll give them that.. oh and the Gree is only 4 stars rated but at RM2150, its s bargain!!! But I still cant say how it will fare long term vs heavyweights Panasonic and Daikin.. LG is a good option too, but its quite pricey compared to locally manufactured Panasonic and Daikin (when compared to LG’s 2.0hp dual inverter premium).. the advantages include ability to control your compressor speed (at 40%, 60%, 80% or 100%) and that it has a lower operating frequency (circa 3400 btu at its lowest vs 3750 btu for the Pana x-premium… the difference is negligible though)… the LG only has 4 star energy rating though ( cant confirm this, but seen it somewhere before)…
Anyways do research and good luck on your purchase!

Im already install this x premium model 2hp in my master bedroom. Just wondering:
1. My room humidity keep above 60%. As i know the i auto-x function help reduce humidity below 60% right? Already using i auto-x function on 28 degree but humidity keep above 60%. Any tips?
2. How much your average kw use for a month for this model? How many hours per day average?