If I change to Red Pitaya, how much time does it take to set up everything for an expert, and for a casual user who knows Linux?
Setting up the RP16 as an 16-band SDR is easy using Pavel Demin's Alpine Linux image:
copy apps\sdr_receiver_hpsdr_122_88\start.sh to the root directory of the SD Card, and you are done with the Linux part unless you want to use both antenna ports with different antennas. Of course you have to start with a blank or reformatted SD Card; you can't simply use the SD Card that is included with the RP since it has the Ubuntu OS partitioned in a way that is incompatible with Alpine Linux.
What takes more time to configure is CWSL_Tee and CWSL_Tee2 on the Windows side so that you can skim 16 slices in two receivers and use a program like HDSDR to get a band scope to look for broadcast band overload while simultaneously skimming RTTY, FT4, FT8, WSPR etc., using the same shared receiver slices.
Start with these instructions for simple 8-band skimming
Automatic the rest usually requires my help since it's quite complicated and there are a lot parts to configure to make it all start in the right order.
Since Red Pitaya has no bandpass filtering, is it easily blocked by TX signals on any band?
Yes. A Receiver Guard like the DXE RG5000HD is essential to protect the front end of the RP.
I gave up trying to block all the bogus spots and I simply terminate everything whenever I operate a contest here.
73,
Bob, N6TV