HP 8643A vs. 8644B?

[0culus]

Been looking at better performing RF sig gens to replace my 8657A. Other than the seemingly very high prices commanded by 8644s, what are the meaningful differences between these units?

8643As seems to be quite more hobbyist budget friendly. I do understand that they are massively heavy, though most of my test gear seems lightweight after getting an 8568B. 

Potential other options? I definitely want sweeping, which the 8657 cannot do.

[0culus]

Decided to look at 8664A's too. Not a whole lot more bones for more signal generator.

[Neomys Sapiens]

I really really wish that someone would take to the chore of making a nice large spreadsheet of them all.

Ok, frequency range, output level from/to and modulation types are easy. But it should include not only more parameters, but also non-numerics like input method, type/size/number of displays, sweep y/n, etc.

If someone started it, I would contribute some data.
Focus on HP and R&S, then spreading to the remainder?

[0culus]

Once I have more time on my hands (give me a few months) that might be fun to do! 

[siggi]

Been looking at better performing RF sig gens to replace my 8657A. Other than the seemingly very high prices commanded by 8644s, what are the meaningful differences between these units?

Here's a document that compares the 8643A-8665s.
https://www.atecorp.com/atecorp/media/pdfs/data-sheets/hp-agilent-8643a-44b-64a-65ab_datasheet.pdf.

I'd guess the 8644 is expensive because it has much lower phase noise than the 8643A - which was the "budget" generator of the series. Note that the sweep on these is discrete, these generators only do narrowband continuous-phase sweep.

[0culus]

Yeah, looks that way. I'm looking at an 8664A right now. Has 3 GHz, so it covers a little more spectrum.

[Neomys Sapiens]

Ok, I ought to see it when this thread is updated or trigger me by PM, I'll gladly enter what I have.