OS X doesn't finish writing to the SSD until the light starts pulsing, but as you say moving the laptop before this with an SSD is probably fine.
Something to be wary of though is that removing devices (e.g. USB) during this period can mean it doesn't sleep properly, or wakes which you might not notice if you've run off with it.
To be safe waiting the 3 or 4 seconds until its done isn't much of a hassle tho really is it?