I have the MSO1074Z-S, and have used it fairly extensively for serial decoding.
I also have a number of USB based LAs like Saleae, Logicport, Bus Pirate, Digilent Analog Discovery.
Be careful about what is read into Dave's video about whether MSOs are worth it or not. Yes, you can get a DSO and a USB LA for less than an MSO, but read on...
While I know I'm swimming upstream on this one I almost always prefer to use a scope/MSO for serial decode. Why? Because the triggering facilities are far, far better than any of the LAs I mentioned, and it's common for me to want to time correlate between analogue and digital channels. The only exception is with very parallel busses which are becoming less and less common nowadays. Also note the limited sampling rate with some of these LAs, depending on your application that might be quite a drawback. A further benefit of the MSO1074Z is that it will sample up to 1GSa/s (0+8 ch, with trigger off digital channel) which beats any of those LAs I mentioned.
Be aware that to hack the MSO variant, unlike the DS1000Z, you'll need to physically disassemble them and use a JTAG emulator. It's not hard, but put aside at least the best part of half a day if you've never attempted something like this before.
Regarding the comment earlier about having a state clock, yes, of course you're not going to see a beautiful 50% square wave sampling a 100MHz signal at 250MSa/s with a 1 bit ADC, the same applies to most USB LAs in that respect, although the LogicPort supports that, although at a lower samplig rate. In practice the high sampling rate of the MSO1074Z means it's never been a particular concern of mine. I've successfully decoded 50MHz SPI on it, and I2C works reasonably well on both analogue and digital channels, but be aware that you can only decode a limited number of frames at a time. I did a YouTube video about I2C decoding here...
Take note that the MSO1000Z is either 4+0, 3+8 or 2+16 channels: an analogue channel is lost for each block of 8 digital channels. In practice thise is rarely a problem, the screen is already busy as it is.
The LA portion of the MSO1074Z does have a few quirks when you start using it with much gusto, I was decoding and triggering off a DDR bus a few months back out on site and found a couple of "features". They were obvious, but still it took my attention from the work I was doing. This is documented here but might well be fixed now, I haven't retested since perfoming a firmware upgrade in the interim.
https://www.eevblog.com/forum/testgear/rigol-ds1000z-series-(ds1054z-ds1074z-ds1104z-and-s-models)-bugswish-list/msg727413/#msg727413So in short, some people prefer USB based LAs, and I can understand that, the amount of screen real estate on your average PC far outweighs that of your average scope. The added benefit with the Saleae is the almost infinite buffer memory, but on the lower models the sample rate is lacking and the trigger options on all of them are very rudimentary, but you tend to use the Saleae in a different way to more traditional LAs, it's more like looking at a post dump report with the Saleae than looking at things in real time.
If you're happy with setting up more complex triggers you might find an MSO a better option for you, certainly that's my preferred option after being a regular LogicPort user for about a decade. I just got frustrated with the lack of trigger options and limited memory on the LogicPort.
Just keep in mind that the screen is limited on the MSO1074Z. It's pretty small for the resolution, so if you're at the bench for long hours, day after day, you may find it frustrating. There is also no post-capture search as you get on the Saleae, so getting your trigger right is more important on an MSO, it's just a different way of working. I use ithe MSO1074Z as my field scope, and for that purpose I really can't complain. Sure I'd like more bandwidth but as a compromise, in terms of features and size it works very well.