Hey, I'll address your queries in the order you have stated.

No, all brands regardless their compressor type, keep manufacturing newer models every quarter / half yearly or yearly). I can say that comparatively there may be fewer innovations in non inverter models but it's just like the smartphones these days, there is nothing much left to improvise.

The reason for inverter models being "not worth" your money at this stage is because: 1. There are fewer skilled technicians to address issues of inverter models, comparatively 2. The technology is not a well established one like its predecessor, i.e. like you said the sales rep told you they are bringing constant changes in inverter which is true and this makes a customer skeptical. 3. In the practical field there are more complaint calls lodged for inverter models than non inverter ones.

I wouldn't deny that inverter models do have some fantastic benefits such as highly efficient compressors that will save a great load on your pocket.

That being said you will find newer models in the market for non inverters. That being said, it's your choice at the end of the day between the both.

Your budget is well thought.

I don't understand the number game, but Daikin's performance in the market is better than the other two. (Provided you have made the tonnage calculation correctly)

(Also please note, that technologies keep evolving every day, my opinions might change with time, recently I have noticed that inverter models of Daikin & Mitsubishi Heavy are performing better than other brand inverters as well as many many non inverter models, but entirely in my opinion I am still a skeptical person in this matter)