I was in the same boat as you about a month ago. I've been riding an XR650R for two years and and didn't think it was all that heavy until I spent some quality time on my brothers '06 wr450f a few months ago. The XR650R felt like a big old Caddy after riding the WR. Nice for cruisin' but I wanted something lighter for trails. Last bike I had before the XR650R some 20 years ago was a '89 CR250 and I needed to know if I wanted another 2 stroke or not so I started looking at 300s.
I picked up a '97 for $1000. PO had the top and bottom end rebuilt and put a new clutch and clutch cable in. He couldn't get the clutch to work and just wanted to get rid of it. Couple hours of my time and the correct length clutch cable and it was up and running. I've now put about $500 more into it for bars, rotors, sprocket/chain, handguards, etc. It seems like a great bike. Since I paid so little I'm willing to give it some more time. While it may be called the 4 stroke of two strokes and does lug well, it really ISN'T nearly as luggable as my brothers WR, and nothing compares to the 650R. That said, it is super light. Also, the '97 seems to be higher geared than any of the newer generation 300s, and WAY higher geared than the WR. I am currently at 14/52, and even 13/52 wouldn't get my first as low as the WR's first.
Jetting at lower elevations was ok as I got it, but everyone recommends going to a #7 slide ($60!) on the '97s and a different needle (I went CEK) which seems to be the biggest thing making the jetting overly rich. It runs great and definitly RIPS.
I haven't been able to ride in too many different conditions, but the suspension is good and seems at least comparable to the WR's on trails. The suspension was redone by ProAction for desert, but was still great in endless bolders on a 4x4 jeep trail we did. In my research I found the fork seals are supposed to be prone to leaking, and mine were when I got it, but running a sealmate through them and bleeding the forks fixed the issue and haven't leaked again after several rides.
I like it and I'm happy I only spent $1500 to test the waters instead of $3000 or so. It looks like crap too, but I'm glad cause then I don't mind beating it!