Months late, but I think this specific hub motor is perfect for building a first e-bike, excluding the cost factor. Very little fab, you'd be running in no time and It'd be fine for light trails. The article says he used a Sevcon Gen 4 motor controller, which you could use for a 'traditional' build later on. Likely whatever battery you chose could be used later on as well.
The battery is always the toughest to sort out. Tesla and Alta and anything decent are using 18650 cells, but there are tons of variants. You'd need three in series and ten in parallel of 3200mah cells to build one of the eight packs from that exodyne, so that's like 240 cells total. The Panasonic NCR18650GA are really good quality cells, but they're about $5ea. You can find better deals on other brands, maybe $2ea or even less. Maybe score a used Tesla battery on eBay and reconfigure it. They're about $1500 for a 444 cell pack on eBay.
The Alta battery is a really impressive 5.8kwh pack. I don't know what the voltage is, but if it were 96v, that'd be a 60ah battery, nearly twice the capacity of the exodyne and only weighs 68lbs. If they used 3000mah cells, they'd need to stuff 480 in there. Pretty crazy, but the weight numbers work out, so I guess that's what they're doing.
Anyway, cost becomes a big problem. You're at $1300 for the hub motor/wheel, $700 for the controller, maybe $1000 for the battery, so you're at $3k for just the core components excluding the donor bike and a hundred bits and pieces. Add another $1k for a blown bike, maybe another $1k for all the other stuff and you're looking at $5k for what's honestly a pretty lame trail bike. You could pick up a fuel injected 2015+ 450 for $5k and it'd be much lighter, faster, with greater range. That's a tough pill to swallow, depending on how you value your money.
So if the dollar-to-performance part is important, then you have to ditch the hub motor and go for the mid-drive so that it'd at least be robust enough to ride it like a proper dirt bike, because I bet you'd eventually cook, or blow that hub motor to pieces riding moto, or rocky, technical stuff. Maybe if you already had the bike, scored a good deal on the battery and could get a plate for it so it'd have more use, then maybe the hub setup isn't so bad. Plus you could probably get a grand for it on resale.