This may be the wrong forum but here goes...

[Big Yac]

I have a 99 KX 500 that I absolutely love.  Recently I've come across 2 bikes here in town for sale and am needing help deciding which to get (I'm keeping the KX, it will never go).  One is a 2000 CR 500, the other is a 98 or 99 KTM 380 EXC.  Both are in beautiful condition.  I've never ridden a CR 500 or KTM 380, they are similarly priced.  Whatever shall I do?  I'm leaning towards the CR because I love 500s, but I hear the 380 has all the grunt of a 500 but not the top end and it has better ergos.  I cannot afford to buy both or I'd go that route.  I'll be riding it here in the Ohio woods in some harescrambles but it will see some strip mines and some motocross track action too. 

[1989kawasaki]

get the 500

[sandblaster]

I like both bikes, so I'd get them both 
If I had to choose one and assuming they are in the same condition I would also choose the CR500.
Don't expect either to be as fast as a K5 but neither are slouches.

[81cr450]

Having had 4 cr500's I bet you can guess what I would say. They're bullet proof low maintenance. Your kx500 wil eat its lunch with the powervalve but the simple reliabilty with healthy grunt mmmmmmm
The difference between the kx & cr in my opinion would be the kx is more like a 4stroke with a broad powerband , but it has funky egros & the frame is kinda cheap. No offence but "all" the little mounting tabs break off, I have even seen one that the upper shock mount broke.
   The cr is great is has more instantaneous throttle response, just snap! It doesnt take lugging like the k5 nor does it have the over rev. It carvs though & has more modern turning & handling. The trails are great but on long straights when you wanna go wide open it really  feels like your ringing its guts out to get 70-75mph, where the kx is alot smoother at high speed with a boat load more mph capability.
   I'm working on a kx500af right now but when its done & I'm flush again I'll pickup another cr500 just for the lower cost of maintenance

 My 20cents anyway

[Polar-Bus]

No offence but "all" the little mounting tabs break off, I have even seen one that the upper shock mount broke.
 

You're over exagerating on this comment. "all" the little mounting tabs do not break off. The ONLY mount tab that breaks on the KX5's  is the upper most exhaust mount. IMO mines' been broke for 5 years, never repaired it, and I see no ill effects by leaving it broke.

Lastly never heard of a KX500's upper shock mount break unless the owner threw the bike off a 100 ft cliff.   

[snoopjonnyjon]

IMO you've already got a KX500 for your 500cc ancient chassis desert racer... and it fills that void perfectly. The CR500 is just more of the same even if it is a little different. Since you want a bike for woods riding, I'd take the 380EXC. It's a more modern chassis, better handling... I'd love to have one.

[81cr450]

On the broke shock mount it was a newer one, 98 or better, know what I saw . &  the 2 k5's I've parted both had "most" of the pipe mounting tabs broke , 1 coil mount,89585999999999999999 I mean how does the coil mount break, the second had the inner nut side of the subframe mount broke. You couldnt call it being from a fall cause it was the inside nut attached to the whole tab. Both of these bike were fairly clean 1999's. Just my expierience, like I said no offence.
 "Love" the motor though 
All in all felt like owning 4 cr5's & 2 kx5's I could give an acurate review. I'm not biased I want 2 of each