I don't own a 1520, yet I'd say seven hours of charging is too long. Are you using the official supplied charger?
My Lumia 1020 charges in roughly two hours using the supplied charger, maybe a bit longer, haven't really measured the correct time myself.
When it comes to pure battery life, the 1520 gets nothing but good reviews. The 1020 however is a different story. I am not satisfied by the battery performance and it is basicly the only hardware related complain I can find about this device. Of course you can attach the camera grip, which upgrades the internal battery by an additional 50%, yet it makes the phone more clumsy for everyday use. I'd first re-check whether the long charging time of your unit is a common thing, if not, try to figure out why it happens.
Personally I can only recommend the 1020 if you really want that camera: Your 1520 has better performance in every way. If it is too large, either wait for the soon to be announced 930 or check out the 925, which is roughly a 1020 minus the camera - yet comes for a much cheaper price.