CLX is definitelly interesting platform but I will not repeat
what you have read already. Let me mention few things that
were left out so far...
We all love more speed, more memory, more everything...
But RSLogix5000 is not quite mature (in my opinion, not
even by long shot) and that's despite many improvements
over years.
Note: We are talking about version 12 and version 13 is
about to be released any day now ("silver bullet").
Yes it can work and it does get job done but even copy
and paste still doesn't work 100% and all the time.
If you have to support many customers, be prepared to install
couple of different versions because not everyone has time
and money to keep upgrading each CPU every 6-12 months.
CPUs come with only 200 byte of firmware, the other 20Mb
you have to load yourself. That's fine if you have other
rack at hand with loaded CPU and fast connection such as
Ethernet. It's only too bad if you have to do it on
customers site, on week end when this the first CPU they
got - because you are about to spend few hour(s) on
downloading via lousy 19.2kbps.
Higher speed is possible of course - with additional cards
and usually only after you had to spend the time to download
the firmware to the CPU. The mentioned communication card
costs extra so don't write off the SLC505 just yet.
CLX as hardware platform suffers from thermal problems.
In one machine with a rack populated with CPU and 4x M02E
cards we had to exchange all of them over past 4 years - despite
plenty of room, decent cooling and no other active components
in the cabinet - except the 24V power supply (100W).
The problem was finally resolved with array of small fans
sitting on top of the rack - strapped with cable ties to
the rack perforations.
The picture I painted is slightly on the dark side but I guess
it's better if you find out sooner...