I'd be around the 20 year mark since my first mort. Part of my statement is also using my uncles advice as he watches these things carefully, and probably has another 10y on me.
On the upward trends the banks will also attempt to average that out so they aren't making less as well. The way I see it, is if you need the security of having a consistent mortgage amount every month, then go fixed, and pay the extra cost for that peace of mind. I prefer to attempt to take the cheapest route in the long term, as the fluctuation won't make or break me.
Once again, just an amateur investor/owner speaking though.