Those that don't understand how this company operates and the magnitude of the marketplace will be very surprised. Having spent 15 years in this industry and working daily with the quantum shift in current demand for this product, this is the only public company available to you to participate in this sector. DLR also shouldn't be compared to any other of the commercial REIT's. I think once people start to grasp what this company actually does and the enormity it's potential the stock will actually reflect that. The volume is an example that it isn't even on the radar yet.
Given you have been in the business for 15 years you could do a better job of convincing us why this is a great investment. Although I get it that cloud computing is the future I believe the valuations are not justified given the companies capital structure.
If this company wants to expand and build more cloud computing facilities it will need to raise more money. I doubt that they can raise debt with no cash to put down so they will either need to sell more stock or issue preferred shares with a cost of 6% plus any additional dilution (if there is any). These properties yield about 11-12% gross, subtract the cost of capital of 6% (minimum), subtract the maintenance needed 2-3% and you have 2-3% left for equity holders. That is not a good investment in the same way YHOO and AMZN where not good investments in 1999 trading at 1000 times earnings or that buying a house 3 years ago yielding 2% was not. Capital appreciation of a company ALWAYS returns to valuation (eventually).
The unlevered returns are closer to 15% not 11% in this environment, and when you can raise money in the mid single digits and turn it into a 15% return that is called minting money. True the returns are nothing like YHOO, AMZN, EBAY, GOOG but there is much greater certainty in their cash flows. They can raise cash via debt if they wanted to because they have plenty of unencumbered assests (350 East Cermak is probably the most valuable data center in the world and no mortgage). The other thing you are overlooking and the most important is that same facility growth in rents has been above 20% for several quarters now, and given market pricing due to the imbalance of supply and demand this can contnue for years. Remember most of the leases that are coming up for renewal for the next few years were signed during the tech bust when rents per quare foot were next to nothing and now they are going to get repriced way higher (like 3 times higher in some cases) this built in growth needs to be included in your valuation not just growth via raising money and building new facilities.
All that beign said. At $44 I would not buy any new shares, but I wouldn't sell all of them either, just take some of the profits off the table.