I've been thinking about starting this exact thread for a while, good move.
Now that I know what the I means, is there any advantage to an integrated solenoid beyond ease of install? I've been wanting to relocate mine to near the battery just to minimize the exposure of always-hot cable but an integrated solenoid would take my freedom to do that.
The I series just makes for cleaner packaging but the cost is not being able to upgrade from solenoids to a contactor.