This Pioneer amplifier is a newer model to the GM-3500T. It would be available in the market and probably would be retailing near the 6-7k mark since its a new model (shopkeeper's excuses)
You can find a better quality 4ch amplifier from @krieger in the same range or if not then ask him for a better 2ch in the same range. In terms of quality, the Alpine amplifiers he has are better than these Pioneers.
Components like Pioner d1720c, jbl gto608c, Focal 165A1 SG, Infinity 6030cs would be suitable on a 2ch amplifier with the round about power ratings. These would set you back from 8k to 18k. Depends upon brand.
If you want to change the front speakers, which I am assuming you want to run on the amplifier, go for components. Flush mount the tweeters in the A pillars or sail panel and you are good to go.
Yes, this kharcha would lead to a difference of day and night in your audio experience inside your car as compared to the stock system. Clarity, Quality, Loudness, everything will increase. Yes this amplifier is suitabale as well as any amplifier (branded) with the same power ratings.
No need for reference, collect suffient budget, go to an installer, demo the brands you want, get them installed. Voila!
Hope it helps