However, neither the SMIQ or the ESGD are going to deliver anything like lab grade performance in terms of phase noise or spurious. These are very much economy grade generators in terms of the basic frequency synthesis but they offer lots and lots of features including a vector modulation capability.
I disagree with the notion that ESG and SMIQ are not "lab grade" (which is a silly term anyways), unless you think "lab grade" means "best specs ever in all areas" (which it doesn't).
SMIQ and ESG-D are most certainly "lab-grade" equipment ('lab-grade' does *not* mean offering the best specs possible in all areas), and at new prices in excess of $30k I'd say calling it "economy grade" (a term usually reserved for entry level kit like the stuff from Hameg) is quite a stretch.
But that doesn't change that both SMIQ and ESG-D are pretty much "lab-grade" instruments, and the fact alone that they found use in a huge number of labs around the globe puts the notion that their performance isn't up to scratch for professional use clearly into the sphere of nonsense.
I recently bought an ESGD E4433B for £1k with the dual arb option and several other options. This is probably half the normal used price but the price of these should start to drop soon because they offer limited capability in terms of dual AWG performance/bandwidth and also the Agilent support tools are pretty lame (obsolete). So many companies will be moving over to the later MXG type generators.
That cycle has passed many years ago already, at least for the first generation ESG-D (B models). At the moment its the later ESG-D (E4438C) that are being replaced.
The same is true for the SMIQ, which has been replaced with the successor (SMU) a long time ago, and similarly this successor is now slowly being replaced with the current modell (SMW).
Most of the ESG-D B models and SMIQs on the market are probably coming from second or third hand users.
AFAIK the SMIQ is inferior to the early ESGD models in terms of AWG performance
Can you elaborate? The only difference between the AWG in the early ESG-D models and the SMIQ is the sample memory (512k/ch on the SMIQ vs 1M/ch on the ESG-D), and both values are pretty tiny by today's standards anyways.
The second generation ESG-D (which is more comparable to the R&S SMU200A) offers a much better AWG performance, but that clearly comes at a cost.