Yes, I do wish that the Keysight had more data memory and could do longer FFTs. One of my planned projects is an open source interface to R where I know that I can do long FFTs quickly as well as do other signal processing and statistics. Unknowns are how quickly I will be able to get data out of the scope via the LAN interface and display the results (way slow compared to the scope for sure).
Well, the DSOX3kT has an optional (yes, you have to pay
extra for that
) Ethernet port and that is 100Mbit, which isn't much. The other alternative is the built-in USB2 port, which is also slow.
Only you can say if that is sufficient.
I had considered buying a much lower end scope but was swayed towards Keysight by their educational videos, Scope Month, and the trade-in offer. I probably had the maximum number of entries possible for Scope Month and was in Dave's supporters drawing to no avail, but I might be buying the new scope for less than the tax on a fully loaded MSO3104T prize.
Any reason you focussed on Keysight? Because in this very scope class the most bang for buck is the LeCroy WaveSurfer 3000, which offers more and costs less. You get more memory (10Mpts, and 1Mpts FFT), a larger screen, access to a wider range of probes (LeCroy doesn't artificially limit probe compatibility), and you don't get gouged for things like network and monitor ports, something that should really be standard these days.
LeCroy regularly does trade-ins and you might even be able to get the MSO option plus all options on top of it. If you really want to trade in, as usually just selling on the old scope and buying the new one without trade-ins is the better option.
Just sayin...