Never used a payment plan and my experiences are a mixed bag. They are really super nice to communicate with, but rather dismissive with complaints. Their stuff is top notch, but only if they get it right.
Sadly, in my experience, they lack a proper control before they ship stuff out. I had to return a Sonic twice before it was in proper shape and that just shouldn't happen at their prices. But at least they fixed it both times rather quickly. Still, it was over a year from first payment to final delivery.
When I ordered a Tardis Console stand for the Sonic it arrived with a nasty scratch, which they put down to normal production errors and no cause for a return/replacement. That thing is a machined lump of aluminum, so yes, the machine can leave marks, but this scratch was deep like someone used a nail on it.
Next and probably last was the Mini Moment. which had a crack at one of the joints and several places where the paint had already fallen of. Since I really liked it and it was out of stock I bit my tongue and just kept it.
So, three purchases, three faulty items, not a good record, especially given their prices. They'd have to come up with something really amazing before I buy from them again.