I’d like to say that I have the most dirtbike knowledge and experiance on this site… so…
if you have 6,500 to spend on any dirtbike
The top 4 manufactures (honda,suzuki,kawi,yami) make the best bikes and they are now minimal differences in both their 250cc and 450cc dirtbikes
With the exception suzuki is going Fuel injection on their 450’s
If you are looking for a motocross bike… go with a 250F. The 450’s would be a bit much for you and I doubt you will use all the power.
A full out motocross bike isn’t the best for trails but it can be used for trail riding with no problems.
Check out a honda crf 250x. it’s the motocross bike with a few changes to make it trail friendly
Stay away from 2-strokes. they sound cool, thats about it. Everything is going 4 stroke for a reason. they are better. and the wieght difference is minimal…you won’t notice it unless you are a supurb rider.
My 2 cents’