Well I happen to be in a unique situation actually. I recently have had the option to rollover my 401k to a new brokerage firm. I have been selectively selling off each investment one at a time to maximize the sell price (yes, market timing). This may seem like a bad idea, however the 401k I was in had a VERY limited basket of funds in which I was able to choose from. These funds perform poorly compared to the ones I could be picking (and will be in my new IRA) so every penny is needed. The basket of funds was some form of precautionary measure used to prevent idiots from losing everything and blaming the company for not having a retirement.
I have a good understanding of the financial markets and think I am pretty grounded in my decision. I am about to start spending more time researching these picks once everything is set in stone - but I feel comfortable laying off for a bit since I sold at a peak.
I do my best not to purchase my own employers stock either - its a bad idea because you become too attached to the loyalty and become less objective.
Owning a large basket of stocks (modern portfolio theory) is a good idea, but don't base it on silly characteristics like beta. You have to make sure the underlying business makes sense, has trustworthy management, and you purchase the companies at a significant discount that you have a good margin of safety. Ok, it is pretty obvious I'm a value investor - but I learn from the best (Warren Buffet).
It looks like you have done pretty well for yourself, I'll make sure to keep my ears open.