<<I have noticed that my value or account balance reported has dipped when I went to the 80% mid cap /20% company stock...
I am cheap and hate to 'lose" money>>

If you hate to 'lose' money then you have theoretically reduced the risk of losing money by moving 80% of your 401k from a single stock to a mid-cap mutual fund (because it is diversified).

But, if the stock climbs 1000% you have 'lost' that opportunity to gain on 80% of your 401k. So, I think your allocation depends on your tolerance for risk. It sounds like you are 'sweating' short-term dips, so you may sleep easier with your 80/20 allocation and not put all your eggs in one basket.

<<Have I actually lost that money or is this virtual represent of the market value if I was to cash out today?>>

Your gain or loss is determined when you sell. Your portfolio may be down 25% today and up 25% next week. Your balance is representative of today's market value, that's all.

Good Luck!

CMUspirit