In recreationl riding there is no starting gate, need to ride "all out", 4 ft tall trophy or $1000 at the end of the ride. Most recreational riders don't want to spend or have the money to put into their rides that racers must. We buy bikes, take good care of them & hope they bring us years of reliable service.
To me, this boils down to choosing a machine that will do what I need it to do, one that I can have fun on. It's all pros & cons. Like duel sport bikes. They are not awesome both on and off road, but they can do a bit of both quite well. If you want the most awesome trail bike, that you can make the very best times on, then get the 250, put the grand into it to wake it up & ride it hard & fast. You will be able to negotiate tight mtn trails much faster than on the 450. I don't know anyone who can get on a 125 in the woods & pin it for very long before they t-bone a tree. Handeling and suspension
allows you to go fast in the woods. On the flip side, there aint a 125 or 250 that can hang with me in the hills.
We were camping one year. My buddy & i were on XR600's, piped & geared. My wife had a stock XR250. We had her time us on the big bores. It was an awesome single track that went up and over a mountain, steep, twisty, increadible, probably 12 miles over and back. I switched to the 250 that I had zero seat time on & couldn't believe how light & nimble it felt. (Did I just say an XR felt light & nimble??? dam I'm old, lol.) I smoked my best time & had more fun doing it.
If the need for speed isn't that important, which it certainly isn't for me, I would buy the 450. 1st off, EFI is the chit. But more importantly, I like a geared down 450 to get as much torque as possible. Hell, they have almost taken the thump out of the thumpers. Rotating mass is half of what it was back in the day. Crap, remember when you could lug up a steep twisty trail on the old XR600 in the wrong gear, (one gear too high) LOL?? For as heavy as that bike was, I think it still made you lazy. It did all the work for you & if you were too tired to shift into the correct gear, so be it, it pulled all day. Ya the clutch pull was a bear, but it didn't matter cause you'ld only use it a dozen times a day.
Another reason I like the 450 is cause I don't want to have to wring the thing out all day. I ride big hills on my 450's. The boys on the 250's are on the rev limiter all the time. I think I hit mine twice last year. While they are adjusting valves & doing top ends, I'm riding wheelies at 5000 rpms, lol. . I think you get so much more for your money in an open classer. Just look at the size difference in the chains.
It's your choice, for me, it would be the big bore all the way. I'm not slow as a snail, but I don't ride all out anymore.
Let us know what you get, pics please!!