I am a current customer.  I sent them my servers in April, about 40TH.  So far they have been "slightly" more expensive than running the servers myself, but with less billing issues from the electrical company.

You can set up payment to them in either BTC or dollars.  I prefer the BTC to pay as then I can track both revenue and expenses in BTC.  Yes they have HST (harmonized sales tax) on their service, but that is part of the monthly cost.

They do not have 99.9% uptime, I would guess several hours a month of downtime with ~10 power outages in the last two months as they have been upgrading their facilities electrical power.  Power outages make my servers complain (Spondoolies sp30s have issues rebooting themselves sometimes and require a human present to swear at them) but the price, in a data center, is far cheaper than it would have been in a local (Edmonton, Alberta) data center.  If there are power fluctuations they are pretty good about resetting the servers quickly, but, as I said, sometimes the servers don't like to come up again and need a harsh talking to.

The internet connection in their data center is a lot more reliable than the internet was here in Edmonton, (I think GN's internet went down only once or twice for a few minutes in the past few months) but that is likely because the infrastructure is newer.

They run the servers on Eligius, so you can watch your page and let them know if there are any oddities.  You have to give them the server passwords so they can set up the machines in their data center and do the reboots after power outages.  You can't really visit the data center, as Churchill falls is in the middle of nowhere, so you have to have an element of trust, but, so far, I have had the same BTC revenue using them as I did when I was running the servers at my own place.

So far I am still ahead a little in BTC each month (revenue minus data center costs to run servers), but it will take about 44 more months to recoup the initial cost of the servers plus setup expenses.  Will BTC be around that much longer, and what will the value of each BTC be then?  Not sure.  Also getting off topic.