We LOOOOOOVE offsite. We stay at Windsor Hills - 5 minutes from the park. Luxury villas and Condos - much nicer than most onsite Disney hotels, in my opinion. It's not just the cost savings. We love the space, having our own personal pool and hot tube outside of our livingroom (as well as the resort pool / waterpark), not having to walk to get to get to our room like onsite. Just park in our driveway

You are, quite literally, paying the exact same price as a value resort room that sleeps 4 to get an entire luxury home that sleeps 10 or more. It's about 1/10th of what you'd pay per night for a similar villa onsite.
I find the transportation aspect easier and quicker than onsite. Many of our friends wait 20 minutes for a bus, than another 20 minutes back to their hotel while onsite - then however long it takes them to walk back to their room. For offsite, it's a quick walk or tram ride to our vehicle, a few more minutes drive and we're back at our villa. EASY!!
I will say - if you're planning a split stay, you will be able to take advantage of all of the 'perks' of onsite for the entire length of your vacation. For example - if you book a value or a campsite for even the first night of your trip (even if you pay for it but don't stay the night), you will get magic bands, free parking for 2 days, plus the 60 day fp booking window.
You might find this thread VERY helpful:
https://www.disboards.com/threads/throwaway-room-offsite-to-onsite-stays-update.3539209/