typical DSO=TDS220
Yes, but today we have better digital phospor scopes with 1 000 000 waveforms per second (DSOX3000 series). There will be no problem with looking at audio-modulated RF envelope.
The problem with many DSOs looking at an audio modulated RF envelope has little to do with waveform update rate - it has to do with the aliasing / under-sampling of the carrier when the horizontal scale (sweep speed) is slowed enough to clearly observe the audio patterns. Some DSOs give you ability to change the sample mode to +/-peak to try to compensate.
Still, an analog scope does excel in this application.
This ain't a problem if you implement sampling at low sampling rates right. Let's assume that the ADC always runs at full sample rate. At low sampling rates you have many superfluous samples. What to with them?
1. just take any nth and discard the others and get aliasing
2. store min and max and loose statistical information
3. average: brings down the noise level, but you loose high frequency content
4. take a random sample: you don't get aliasing and retain statistical information (where the signal spent a certain amount of time)
HP published an article on this in one HP Journal issue, don't remember which.
Anyway you don't have to care about this when using a recent DSO such as the Agilent DSOX series, which give you an analog-like display.
Concerning analog scopes:
If you need high performance and flexibility and don't have a massive amount of money, a used analog scope is pretty much the sole option. I paid less that 100€ for my tek 7834 with Plugins. With a bit of adjustment (reduced scan, fast storage mode) you get 500MHz single shot bandwidth. The other extreme is the 7a22 plugin with gives you sensitivity down to 10µV/div at a bw of 1MHz. That's unbeatable value for money, even it would have cost 1000€.