If I give my opinion a bit more firmly it might help
The R4131D is (to me) a very poor analyser and I wouldn't want it taking up space in my house. Simple as that.
The LO system it uses isn't synthesised (so it isn't accurate when measuring frequency)
The RBW only goes down to 1kHz.
I doubt the linearity spec is going to be good.
It only has a 70dB dynamic range and it only has an 80dB display range.
I doubt it has a 1Hz noise marker function and it doesn't have an internal TG option if you want a TG.
A newbie to spectrum analysis will have a lot more reward from something like the Rigol 815TG as long as they don't expect it to perform like a lab grade analyser.
It has a modern user interface, modern connectivity and a nice display. The RF performance isn't that great but it has been cleverly compromised to meet the needs of the keen hobbyist or small business and it is available new at a remarkably low price.
But you can't really compare the 4131 to the 815 as I doubt the 4131 will cost more than $500 used and even then I'd rather not bother. To me the 4131 is so poor (technically) it has virtually no value to me at all.
By contrast I would certainly give up space in my house for a Rigol 815 because it is so portable and I would find use for it for casual measurements. I wouldn't want to buy a new one though because it would only get used rarely (I have several large and heavy lab grade analysers here) so it wouldn't be cost effective for me.
I would love to have a Rigol 815 here for technical review but I doubt I will see one any time soon...