Thank you Arhi for your answer.
I'm more and more looking at the PicoScope 3206B (200MHz, 128M memory). Compared to 200MHz scopes, I checked the Rigol offer, and they sincerly have a very nice 200MHz scope (DS2202), but it's a bit expensive http://www.batronix.com/shop/oscillosco ... S2202.html
I heared excellent feedback about this Rigol thing and I'm very tempted to buy one. Compared to low end scope from Agilent (2xxx series), it has a lot of features provided as (very expensive) options by Agilent (or Tektronix).
So the problem for me is that for 1000 euros the choice is extremely difficult. 1K euros is beyond the high end amateurs/hobbists scopes, but it does not let you buy a trully useful tool for professional use.
From another side, the Agilent have a nice feature: when you buy the low end 70MHz version (in the 2xxx or 100Mhz in 3xxx series), you can later buy upgrades to higher bandwidths (as bandwidth is limited using software in those scopes, the hardware is the same). WIth the Rigol 2xxx series, you are locked to the bandwidth you buy, this is why buying a 200Mhz is mandatory for me since now (I really need only 100Mhz but I'll need the 200MHz for a big project comming if few months this year).
The PicoScope at 1080euros is the only 200MHz scope I found at this price providing a huge buffer, all serial bus decoders, and a nice set of triggers, and an arbitrary wave form generator. What bothers me with this scope is of course the fact that I'm really used to use physical knobs and buttons to quickly change the scope settings (mainly zooming and triggers) at work, and with a windows gui and a mouse I cannot see myself doing things quickly.