A very important part of repotting is how the plant is handled afterwards. Keeping a plant on the dry side and raising the humidity is a good idea. Many of the roots will be damaged simply by cramming them into a pot with new mix, whether you trim them or not. Keeping the mix on the dry side, raising the humidity and shading the plant all are meant to keep damaged roots from rotting and minimizing dessication while encouraging new root production (branching).
Timing is also important. If a plant is about to go into a root producing cycle from the newest leads, the plant will quickly re-establish in the new mix. The best advice I've read is to repot just before your plant is about to make new roots. However, this requires a period of observation and the willingness to repot at any time!
Another trick is to underpot a newly acquired plant so that there is no room for new growths. This helps to minimize the effects of overwatering a plant with a damaged root system. After the plant has established and is beginning to make new growths, pop the whole rootball into the appropriate sized pot for 1-2 years continued growth using the same mix. This method has worked well for me in the past.
Thanks to all for your attentive responses!!
Bayard - sounds like a lot of good advice; will remember to keep underpotted, dry but humid till new roots appear!!
Duane - thanks to you too, will remember your earlier note on the trimming issue
And Gin - yes, will always remember not to plant the cattleyas in full hot sun in garden dirt
Now, I'm off to plant the bare root catts!!!