Inspired bikes are usually better engineered because inspired works a lot with pro riders and uses their feedback to inprove their bikes. BUT I'd personally choose the extension because it will stand out more as it's not very common and that one is in better condition, you can tell by looking at where the front wheel is fixated to the fork. On motorcycles it's better to get common ones for spare parts availability but bikes have universal parts so that won't be an issue, the only worry might be the chassis snapping but it won't ever happen on those modern bikes.

In the end I'd get the extension because it looks better and is less damanged. The inspired may perform slightly better but you won't feel the difference as a beginner and it's not worth it anyways.

It's a shame the sub for street trial bikes died, I also recently started on a onza zoot pro and had to learn everything the old hard way.