As an owner of Keysight scope I agree with most of things you said.
Problem is that first Keysight scope that has RT eye diagramming and jitter analysis capabilities is Infiniivision 6000 series, and that one, 2.5GHz, used with no warranty in Keysight used shop is listed at over 13000 USD, with NO options whatsoever. You could haggle a little, get warranty contract, buy options, haggle a little more but I doubt you could get one with full options and warranty for less than 14000-15000 USD. I agree that is a much more polished scope with more measurements and proven quality, but it's also twice as much money.
That is why people are tempted by Rigol and Siglent. It's not that people think they are superior to Keysight or LeCroy (as long as you dig a bit deeper you see they are not), but if they are good enough to do your job and cost much less then big brands, many will find them exactly that, good enough...
Absolutely agree 100% with your observation 2N3055
Four quality low jitter measurements with eye diagrams you are looking at either the following scopes from the usual suspects the Keysight 6000 series, R&S RTS2000 series or the Tetronix MSO54 or for better accuracy the MSO6000 series
All of the above start at £17K for a four channel 1Ghz basic model with no apps or relevant probes.
The Tek MSO54 1Ghz is £17400 + 5-DJA jitt er package, £4K plus 5-PWR power analysis at another £3K and 5-SRAUDIO I2S and L-R justified for £1800 plus vat gives £31400 inc vat, yes they will talk a deal, but as with every company there is a limit. yes the vat we calm back but its a significant outlay. This doesn't include the current and active probes required for power analysis.
The Tek MSO6000 is a more desirable product as the accuracy is improved over the 5000 series, but its £33k +vat
Similar sums for the other respected manufacturers.
The question is do you really need that extra performance for that extra outlay???
Blueskull did you twist a few arms for that pricing for the Keysight 6000 series
Happy to have to quality used scope no problems they just do not seem to appear on the market when you require one.
Thanks for all the replies so far.