I've been shopping around for a new scope, and it looks like Keysight is willing to let me trade in my old Rigol 1052E for 30% off a new Keysight scope. (Unfortunately, it's not combinable with the free signal analyzer upgrade promotion). Is it a good deal?
30% off for a simple 1052E is a very good deal from Keysight in my opinion, however I guess it's off RRP and as you say you can't combine it with other promos.
But since its based on RRP I'd check the current street price for the Keysight scope you're looking into, and do a bit of research as to how much you can get for your DS1052E is you sold it individually, and then do the math.
How much below MSRP is typically quoted for Keysight scopes?
That depends who asks, the mood of the sales droid you're talking too, and how good your negotiation skills are.
For most of my applications I could probably get by with a Riglol'ed Rigol DS1054z, but I hate the noisy Rigol fans and the Keysights are pretty quiet.
If fan noise is your only problem with the DS1052E then replacing the scope just for that would be a waste of money when you could just replace the fan with a better one for a few bucks.
If you go the new scope route however then I'd also ask R&S if they can match Keysight's offer for the HMO, which are great scopes that are absolutely quiet and certainly worth considering.