Just got one, so I'll report once I've installed it. I don't want a topping lift, but don't like the boom dropping when I don't have the main up either so it looks like the right way to go to me. I trailer and remove the boom so I'll report on how it adds to rigging time as well.
I put a boomkicker on, adds about 5 mins to the setup. It's nice to keep the boom up, but, as far as sailing, I'm still too new to know if it helps. I'll be hanging one of those lines from the back stay this year. The boom will still tend to swing side to side, even though it is supported, so that back stay hook up will hold it up and out of the way.
I helped Bastonjock acquire and install his boom-kicker on Glissando back in 2008. Fairly expensive...at least compared to a standard boom-vang and topping lift. Pain in the "arse" (as my good Scottish friend would say) to install. It ripped the goose neck off the mast the first time out that we used it...and the winds were not that strong. Maybe he will see this and chime in with his £0.015 worth...
To be honest I just don't see where it is much of an advantage. And just seems to me to be one place you can save some $$ for other more useful mods like a wheel-pilot...
However, if you have a large roach main (like maybe the musclehead) then the boom-kicker might prevent any sail/topping lift interference.
Best money spent on the boat. Do not know if it improves sailing charactaristics but in light air it prevents the boom from jumping around.
Long may your big jib draw.
Rick
On larger sailboats, I can see where these would be more useful when there is standing room under the boom. On the Macgregor, it really doesn't make any sense as a boom vang will give you the same performance for much less money. The topping lift will allow you to life the boom way up in the air so you can freely move about the cabin without hitting your head on it or ducking around. You can tie off the topping lift to the mast when sailing (to keep it out of the way) or put a flag on it as many do.
I think the boomkicker is overkill on the Mac. I took mine off when I bought my previously sailed 26M. It had a boomkicker, boom vang and a topping lift. Now just the boom vang and topping lift. All is well.
I have a boomkicker and find it very useful in light air, as it gives the mainsail more draft. Also, when reefing, it eliminates having to tighten the topping lift. YMMV.
~Rich