Being an e-27 owner and also a sailing instructor who taught on J-24s
for many years and also crewed on one when I was a teen I know them
both very well.
I loath the whole rating system and I'm not expert enough on it to
tell you how well the e-27 is rated. I think the answer will lie in
the conditions you sail in and how well each boat is suited to those
conditions compared to it's rating.
Is it easy to sail with 3-4 people? Sure! The fewer crew the more
skill needed of course. Like the other ULDBs of it's day it is
designed to accelerate it's way out of high-load situations. When it
hops up onto a plane downwind your speed increases so much that the
loads stay light. This is a huge difference between it and a J-24
which is a bit wide, a lot heavy, and doesn't quite have a flat
enough bottom for sustained planing unless it's REALLY windy. The J
is a maneuverable boat, but it's more of a "surger" than a "planer".
Take a look at the article "Squall Busters" on this site and ask
yourself if sailing down large seas and high winds with the spinnaker
up at night and your only crew asleep down below sounds like a good
idea on a J-24. =)
The e-27 is a much smoother boat to sail than a J. The J-24's rudder
has about as much design to it as a plywood board hung off the
transom. The e-27's is well balanced and better shaped. The boat
balances well, points high and of course goes really fast downwind.
One thing about racing, ratings etc... in my opinion the cards are
stacked in favor of a boat that can plane sooner and longer because
planing breaks the hull speed equation. If your racing venue features
waves and long downwind legs I'd much rather be on an express 27 than
a J-24.
Feel free to ask more questions.
-Bryan