I was for standalone instruments since a few days ago, when the summer days went so hot that I can't turn on the standalone oscilloscope, and power supply, and generator without making the room too hot to bare.
Got back to a wall adapter and a 3v3 LDO instead of a lab power supply, soundcard instead of generator, and a small 1MHz handheld oscilloscope (no more than a microcontroller with ADC and an LCD) instead of the oscilloscope. Most of the time is spent developing software anyway, so don't need 3 lab instruments humming all day long doing mostly nothing but heat.
I'm thinking of making a more permanent DIY setup to replace the lab instruments:
- a few adjustable LDOs as a power supply
- a small analog functions/signal generator
- maybe another MCU as a logic analyzer
- a few LEDs to probe logic states
things like that, nothing fancy, and anchored all together on the same platform so to be easy to probe without the harness of extra probes and wires going to all the lab instruments. All low power and with quiet/passive cooling, no fans.
An Analog Discovery looks tempting, though at that price I'd rather cobble something from whatever parts and devboards I might already have at hand.
As for your question about the oscilloscope, read the user manual to see if it can generate UART signals (probably not) or other kind of arbitrary waveform that can be used to emulate an UART Tx.
It would be much easier to use yet another Arduino (or whatever other board/MCU you prefer) to generate UART/I2C/SPI or other digital patterns, or maybe a logic analyzer that can also generate digital patterns (IIRC "bus pirate" was able to do that, but I don't have one
https://en.wikipedia.org/wiki/Bus_Pirate ).
When I've bought my oscilloscope, the LA option was 3-4 times more expensive than a standalone LA, so I've bought a standalone logic analyzer and never felt the need for exact correlation between analog and digital timing, so I don't think LA+Analog traces on the same screen would be a big advantage.
Of course, it all depends on one's needs, so buy what appeals you most, but don't break your budget for whatever shiny feature. No instrument will cover all the possible needs anyway.