I can't praise Telonic and Rigol enough. When I enquired about this unit, Jim let me know when it would be in stock and then later emailed me to confirm. The unit was delivered next business day as promised by DPD. All very pleasant and professional.
As for the DP831, it works great. I have no complaints as it meets my needs and then some. The form factor is quite large, but this was not a surprise to me. If you want to see it in action, I recommend Youtube. EEV Blog does a solid review of the (very similar) DP832.