Tu inglés es mejor que mi español!
I had a 2009 335i. no performance packages, but I really enjoyed driving that car as a daily driver. at various times, I had a Cobb tune on it, and that probably added 50-60hp based on Cobb's data for the tune that I used. My subjective impressions: Tuned, the BMW accelerated similarly to my new Q60 RS, which would make sense based on the weights of the cars and the HP numbers. I'm still being nice to the Q60 as I have less than 2000km on it, so I would say the stock Q60 RS is still quicker. Stock to stock, there's no question at all that the Q60 is quicker all around.
I didn't leave the tune on because the car ended up in the shop a couple of times with issues that I would attribute in part to the tune and the harder driving that comes naturally from having a quick car.
I decided to get a new car because at 80k, I could tell that the 335 was going to cause me heartache. After the warranty, the water pump failed (leaving my wife stranded by the side of the road for 2 hours), and I had to repair a non-trivial oil leak. I could smell a transmission problem on the horizon based on some odd behavior in manual mode. My experience with three 3-series now is that after 70k miles, the problems start.
I didn't seriously consider a 340i or 440i. for me, there's little excitement in those cars as I had a similar one. I think the '09 335i engine is a better engine than the new one (an uneducated opinion but once offered to my by more than one BMW service center employees), and while the lines of the 4 series is a nice evolution, it's not that different than what I had and the interior is not substantially improved/different.
I also wanted sharper performance. The Q60 RS was just a really good option. The M cars are more expensive, with the M4 being a lot more expensive apples to apples. I can add new wheels, tires and catback to my Q60 and it will still be cheaper than an M2 based on what you will pay in the real world.
from my first test drive of a RS, I was impressed. I drove a Q50 RS and liked that. I ended up with AWD Q60 RS, in part because of design and part because that was what I could get that didn't have what I really didn't want (DAS and all the semi-autonomous tech). I look forward to getting into the car every time I go to drive it. It's comfortable and I feel very comfortable behind the wheel. The 3 series is a great driving car, and I don't feel like I'm taking a step down when I get in the Q60. I don't have track training so I'm sure a fair amount of nuance is lost on me, but that cuts both ways.
I would say that the main takeaways from most of the 20ish Q60RS reviews I listened to/read are generally true. The seats are comfortable. it's beautiful. It drives well. it's quick. It handles well and predictably for it's size. it stops when you want.
one the other side of the ledger, the transmission is not as crisp as I want. I drive almost exclusively in manual as the shift points in D are not to my taste. i'm getting used to the paddle lag.
DAS is not an issue as I avoided it. I work for a video game company and can use a guillemot driving sled for Gran Turismo anytime I want. I don't want my car to feel like that.
the parking brake doesn't bother me and I frankly prefer it to a hand brake taking up space on the center console.
lack of cooled seats don't bother me as I live in SF.
The infotainment is a bit dated, but the touch screen is really usable, well placed on the console and has been appropriately responsive for me. and while the feature set is not like, say, Audi's MMI, I have a running list of things that I really use that are way easier to use on the Q60 than on my wife's 2017 Q7, so I'm warming up to it. I have used the 2017 BMW iDrive on loaners, and for me, it would not be a deciding factor in a purchase decision.
I've used Android Auto and I don't think it's an upgrade to either InTouch or MMI such that I would not use it much if InTouch added it. It takes too long to boot and its performance is sluggish. It is difficult to switch back and forth between AA and the car's native tech functions.
So I'm really pleased with my decision and I'll probably do the wheels and tires soon and also consider an aftermarket catback.