Pardon me for my agricultural attitude to all this but for what it's worth heres my sixpenneth........
Questions I ask when going into an unfamiliar farm-strip. (I have yet to land at a tarmac strip that requires any massively different handling technique to normal, even the ones that do look lumpy like Elstree etc)
1. Are the bumps coming straight at you or are they slanted across the r/way? This does make a huge difference in terms of what to expect in the event of a balloon or even once you are rolling to a stop.
2. Are you landing into a x-wind where a ballooning episode could send things fruit shaped el-pronto?
3. What is the landing speed of the a/c? A Thruster is hardly going to be as affected by a lump at 30 kts as, say, a fast and floaty 182 with no passengers.
4. Is the last 150 m UPhill or DOWNhill. I recall landing away from the buildings at Eggesford once on a warm balmy day with no wind........anyone who knows it will understand what I mean.
I do feel that if you try and judge the peaks and troughs then it is bound not to help really, the key is putting it down where you want it (normally about 30 yds behind where it ends up!!!)
Being too transfixed on the bumps only drags attention away from the rest of the job at hand such as flaring, keeping straight and watching the end of the runway coming at you.
I'll never forget going into Westbury-Sub-Mendip a couple of years ago and being so transfixed by the fact that the runway was curved that I almost forgot where I was aiming for, the plane gobbled up the runway faster than I would have liked.
The moments between travelling downhill and uphill always seem to slow the a/c down beautifully. I have always felt this is due to the "compression" factor in the u/c that takes out some of the momentum. You can feel it through the seat and this is the point I would normally apply the brake (if needed). Braking downhill (unless really necessary) never really seems that effective.
All the above relates only to particularly lumpy grass strips, perhaps not exactly where this thread was coming from originally?
IMHO I would say that taking off on strips such as those I am describing takes as much (if not more) concentration than landing.