The DeMarini CF and the Anderson Rocketech Carbonlite are two of the lightest swinging bats out there. If you like the Vendetta, the CF -11 is a worthy replacement, if not more expensive. The Vendetta was roughly $200 new, even paying full retail, while the CF's full retail is double that.
The best advice I received for my daughter regarding bat length and weight was from a former D1 coach. He advised my daughters to load a swing as if they were trying to hit it over the fence. Then tell them to check their swing as if to prevent a swing from being called a strike. If they cannot stop the bat in time, the bat is most likely too heavy.
If you decide to go new, feel free to text me at 631-942-3516 for a very fair deal.
Most don’t recommend going up more than an inch or oz at a time. Also sticker weights are not always accurate so check the bat weight database on here.
My daughter is also 11 and we are running 30...I personally use the knob centered to sternum and if she can almost touch the end with her arm straight out, I'd go there...if the distance from finger tips to end of bat is more than an inch, I wouldn't buy it.