I went solar 2 years ago and I'm very happy that I did. I haven't paid for electricity and I currently have a credit with the electric company so I shouldn't have to pay anything this winter, or next.
I don't know much about the lease option you're talking about but I'd buy if you can find the cash up front.
First, there is no 'maintenance' (or at least only a tiny amount) and the panels have a warranty. Second, once you make the initial cash out lay for the system, the cost of electricity will never go up (for the life of the panels, which is 25+ years). In effect, I pre-paid for 25 years (or more) of electricity at today's prices. From what I understand, there was a recent spike in electric prices (my neighbors were all complaining about it) but my bill was still $0!
of course, you need the cash up front to pay for the system. After state and federal rebates mine cost about $15,000. With the money I'm saving it should take about 6 years or less to pay for itself. Then I'll have 19+ years of free electricity. The only thing that might need to be replaced is the inverter, which could add 1 year of pay back time but I still come out ahead.
Another thing .....I live in MA and the state has a Solar Renewable Energy Credit program to encourage/require utilities to use renewable energy. Not only do the utilities 'buy' the surplus electricity my panels generate (the credit I mentioned above), they also buy 'credits' that they use to meet their renewable energy requirements set by the state...so they pay me twice. I'm expecting a $900 check next week. I don't know where you live, but look and see if your state has a similar program...if you lease, the leasing company would get that money, you would not since you don't own the panels!
Regarding your roof, if the shingles are in decent shape and the roof rafters are up to code, you should be fine. I was told that the panels will extend the life of my roof. Any solar company should be able to tell you if your roof is in good enough shape. And you want your local building inspector to be involved, Make sure to have anything inspected to make sure your roof is solid.