So it's been a while hasn't it?
Well of course I did exactly what I said I'm planning to do and got those ultra soft tires. I wanted to make them dry-road ready so decided to go with W5 compound instead of W3 (also because there were availability issues with W3 in my size). W5 is good for 20-40 deg C temperatures which are exactly what I was hitting when driving in colder autumn conditions. Also they are TW 80 which is... a tiny bit better. I ended up getting Extreme Tyres VR1 in W5 compound. 225/45r17 because that's the only size they're made in, that was compatible with stock BRZ (they're not made in 18" apart from hardcore widths like 245+).
"There is no magic tire that's going to get your Cup 2 levels of performance in that temperature range..."
Well... Apparently it seems there is. And that's exactly this magic I guess. So from the very first day I swapped Cup 2's with those VR1 W5 tires I felt that it is better. A lot. Especially during colder nights those tires were absolutely bonkers. It totally was nearly Cup 2 level of performance but in cold temperatures. They also performed quite well in the rain. But the main reason why I'm writing this today is because I changed to regular winter tires today. And... they're absolute garbage. Even though there's like -2 °C outside they're still garbage comparing to VR1 W5 especially on dry and damp above 0 °C. It really left me speechless just how good those soft semi slicks were in those cold conditions, during hard driving, comparing to regular winter tires.
Well why did I change them if they're so good? Apparently they cannot be stored below 0 because rubber may get damaged and manufacturer told me it's very bad idea to leave car outside on them when there's below 0 deg outside. And that's literally the only reason why I changed them and actually now I kinda regret because I feel like I could stretch definition of "below 0" just a little bit longer but oh well, too bad. Better luck next year.
Anyhow, if they're so good then why not everyone uses them? Well there's few caveats that I came across that may render this option a bit cumbersome to some people.
1. They're LOUD. I mean you know, people say semi slicks are loud, people say winter tires in summer are loud but those - they're LOUD. It's loud level where your tires are louder than engine up to 4k rpm when you're going 40 kph... And mind you, we're talking about BRZ engine up to 4k rpm - car that has almost no acoustic treatment and engine is already stupidly loud. They whine as hell and you can kinda feel how they transfer micro vibrations that are probably result of how sticky and soft they are. They're so loud that I thought they're damaged at first but after few days I just got used to fact that that's my life now.
2. They're fragile. Because they're super soft they also get damaged quite easily. It's probably not really an issue but today when I was swapping tires I could clearly see bruises in tread that were result of hard breaking.
Also TW 80 is quite extreme so I don't expect them to last more than 1 year, tops 2.
3. They're kinda wobbly. Hard slick tires typically have really strong and stiff sidewalls. Those don't really have that as much. I mean it's still good but well, it's not Cup 2 level let's just call it that way. Maybe it's a bit exaggerated by how sticky and grippy they are so when there's no tire slip - tire bending is the only thing anywhere close to slip that you can feel in car.
4. No clutch kicks :< It's just impossible to go sideways with them. Cup 2 are not all that sticky on wet so I could go sideways from time to time when it was raining without feeling like entire car is about to fall apart. Those tires just girp. The end. Always. Even in the rain. Any attempt to go sideways or initiate any form of slip resulted in EXTREME levels of wheelhop and it was just not worth it. After few attempts I just accepted the fact that my car no longer drifts.
5. They're probably quite useless above 15 deg outside. I mean I was easily getting them to 35-40 deg even in really cold temps (like 8 deg outside) and since 40 °C is their upper optimal temperature range I believe they'd simply melt during summer. Also wouldn't really grip and it doesn't make sense to use them at that point. These are cold-only tires. Maybe even more so than "normal" winter tires.
6. Well, it's 3rd set of tires to begin with because they're neither summer nor full winter compatible so there are both financial and labor implications because suddenly you have to swap tires 4 times a year instead of 2 and possibly need another set of rims if you prefer changing wheels on your own, whenever you want.
Apart from that... I can hardly think of any issues. They catch temperature quite fast, you're good after few minutes even in road conditions, even with slightly below 0°C temps outside and once they're above 20-25 deg - magic starts to happen. Of course they stand no chance against ice but honestly - on icy road those full winter tires are kinda sh*t as well, so whatever...
All in all I'm Extremely satisfied with those tires up to point I asked about VR3 W3 for next winter because I feel like those could be used even well below 0, probably even in snow due to tread pattern. 10/10 will buy again. They absolutely devastate Cup 2's in low temps performance.