I'm going to assume you are asking an honest question so I will attempt to give you an honest answer.
The key to your question is "experienced" mountain rider. With the understanding that most people on hear consider themselves experienced riders, when in truth most are not your going to get a lot of "INSANITY".
An experienced mountain rider will make any sled look easy to ride including the Apex. An experienced rider will do things with a stock Apex an intermediate rider can't do with a LW 2 stroke (boosted or not) boondocking or hill banging. The responses to your post have more to do with defining who is experienced, and who is not than they do with how these sleds compare stock verses stock.
You see, it's not about the sled, it's about the rider. I consider myself an experienced rider, but I have had my @$$ handed to me more than once by a more experienced rider on a stock Apex. The answer to your question is if your talking about an experienced rider, the Apex will run with any dog in the hunt. Where the problem comes in is riding an Apex when you are really an intermediate rider. The Apex requires more experience to ride to it's potential than a LW sled does. Your inexperience or lack of ability will be magnified on a heavy sled.
I was watching Boost 4 last night. A few of the guys riding in this film would hand 99% of the guys on this forum their @$$'s on stock Apex's or Nytro's. They may not climb the chutes they climb without boost, but as far as riding goes my guess is they could handle any sled better than most can handle a LW sled. (BTW great video again Veedy, I could watch your filming all night long.)