I'm running 1.19.3, the newest update. Everything has been running smoothly, and I like all the new features that were added in, and I haven't had a crash in atleast 2 versions 
The problem with upgrading now is that it takes too long to redesign parts. If I create an engine, and then wait 4-5 years, that engine's rating will be almost useless. Then I hit redesign, pop out the exact same engine, and it takes a good 8-10 or so months to redesign, which is valuable time. I don't really see the point of an age penalty in a lot of cases, as well. Let's say I build a 5.7L V8 with 400hp, 400lb/ft of torque. A good 10 years later, that engine should still be good, because that will always be a great output. It is more expensive to modify the engines, and it usually throws me into a 1 turn deficit because I click it so much until it just doesn't raise the stats at all, but I don't see the point of having to redesign a part entirely.
If the game were more in depth (like Automation) I could see a use for an age penalty, like using a cast iron engine head, then when you're able to use aluminum, the rating drops, but because the game doesn't go that in depth, the age penalty doesn't really make sense. If anything, the ratings should rise over time. For example, you can release a partwith only so much reliability, then over time as issues pop up, the reliability rating should rise as your engineers fix the issues. It wouldn't make sense to drop the reliability over time, unless you're using an engine designed in 1920 in 1980, then it would make sense. But I like keeping things simple and sticking to a few tried and tested parts. Much like how Ford has had the 5.0L V8 for just about a decade now, and Toyota has had the 5.7L V8 for nearly a decade or so, and they're just about the most reliable pickup engines out there.
Also, what's up with pickups never having enough torque? In real life, an F-150 can tow about 8,000 pounds, and I push out 500lb/ft trucks that can tow 32,000 pounds but when I go to make the truck, the power rating is only like 3.5 stars, and it says "Engine could use more torque." That does get a bit annoying, especially if you're creating different classes of truck.
The problem with upgrading now is that it takes too long to redesign parts. If I create an engine, and then wait 4-5 years, that engine's rating will be almost useless. Then I hit redesign, pop out the exact same engine, and it takes a good 8-10 or so months to redesign, which is valuable time. I don't really see the point of an age penalty in a lot of cases, as well. Let's say I build a 5.7L V8 with 400hp, 400lb/ft of torque. A good 10 years later, that engine should still be good, because that will always be a great output. It is more expensive to modify the engines, and it usually throws me into a 1 turn deficit because I click it so much until it just doesn't raise the stats at all, but I don't see the point of having to redesign a part entirely.
If the game were more in depth (like Automation) I could see a use for an age penalty, like using a cast iron engine head, then when you're able to use aluminum, the rating drops, but because the game doesn't go that in depth, the age penalty doesn't really make sense. If anything, the ratings should rise over time. For example, you can release a partwith only so much reliability, then over time as issues pop up, the reliability rating should rise as your engineers fix the issues. It wouldn't make sense to drop the reliability over time, unless you're using an engine designed in 1920 in 1980, then it would make sense. But I like keeping things simple and sticking to a few tried and tested parts. Much like how Ford has had the 5.0L V8 for just about a decade now, and Toyota has had the 5.7L V8 for nearly a decade or so, and they're just about the most reliable pickup engines out there.
Also, what's up with pickups never having enough torque? In real life, an F-150 can tow about 8,000 pounds, and I push out 500lb/ft trucks that can tow 32,000 pounds but when I go to make the truck, the power rating is only like 3.5 stars, and it says "Engine could use more torque." That does get a bit annoying, especially if you're creating different classes of truck.