So which scope to buy

[mrpackethead]

I've short listed the RS2004 and the Keysight 3000.     I can have 2 2004's for the price of one 3000, but the 3000 is upgradable ( and potentially hackable ) to 1GHz...

[BravoV]

The ethernet eye diagrams are probalby the thing that pushes the spec requirement out.

I'm a noob, pardon for this question, say you got your scope that fits in your need and its fully capable to display the eye diagrams of ethernet signal as you wanted.

What kind of potential problems (just name the common ones), once you have a perfect eye diagram displayed at your scope ? And the potential fix for it ?

[mrpackethead]

I'm a noob, pardon for this question, say you got your scope that fits in your need and its fully capable to display the eye diagrams of ethernet signal as you wanted.

Simplistics, you can use it to determine the 'quality' of a repeatitive serial data stream.   

[tggzzz]

The ethernet eye diagrams are probalby the thing that pushes the spec requirement out.

I'm a noob, pardon for this question, say you got your scope that fits in your need and its fully capable to display the eye diagrams of ethernet signal as you wanted.

What kind of potential problems (just name the common ones), once you have a perfect eye diagram displayed at your scope ? And the potential fix for it ?

https://www.google.co.uk/search?q=eye+diagram+techniques

The wackypedia article isn't very helpful, but the next two are. In general look at manufacturer's application notes.

[mikeselectricstuff]

I've short listed the RS2004 and the Keysight 3000.     I can have 2 2004's for the price of one 3000, but the 3000 is upgradable ( and potentially hackable ) to 1GHz...

MSOX3000(T) vs. RTB2004 is not clear cut - there are significant plus and minus points on both sides so you'll need to look at both in detail based on your requirements. 

[mrpackethead]

I've short listed the RS2004 and the Keysight 3000.     I can have 2 2004's for the price of one 3000, but the 3000 is upgradable ( and potentially hackable ) to 1GHz...

MSOX3000(T) vs. RTB2004 is not clear cut - there are significant plus and minus points on both sides so you'll need to look at both in detail based on your requirements.

In deed its not. It might even be a case of buying both...   The RTB2004 would be a significant upgrade to the Rigol that is on the cal/repair desk.    the extra capabilitys would be handy.  Its almost a decvision that doe'snt need to much mor ethinking.

[alm]

Depending on where you live and the R&S/Keysight presence there, you may be able to get a loaner so you can try them side by side for your specific applications.