We've been Crownline owners now for about 8 years. We sold our older Crownline, which we were quite pleased with but which turned out to be rather small for the new lake we just moved to (Ozarks). We looked at other brands, but always came back to Crownline in terms of fit, finish and quality in relation to price. The only other brand we've found to be comparable is Cobalt, but they are super-expensive. Crownlines seem to have a high value ratio. So, we bought a 2000 266 BR with a 7.4L MPI Merc Bravo III. While it's not exactly a 270, I can tell you that the 266 has produced a soft, dry ride, and I would expect the 270 to do the same.
As far as engine options, my old man always says "there's no replacement for displacement." The 6.2L engine is a great engine, smaller block, lighter weight, and has a similar horsepower rating to larger engines. We considered this when we were looking at our Crownline. The 350 mag has a similar hp rating to the 7.4L, however, in the end, we decided that we would prefer to have an engine that only needed to run in the middle to lower end of its power band even with a full load of people and fuel than one that had to struggle a bit when tubing with 8 passengers, 2 coolers and a fresh load of gas. Our hope is that the larger engine will last longer because it isn't taxed as badly, and further that it will actually burn less fuel (except when we want to open it up to, like you said, outrun a storm).
As an example, we had an old Regal with a smaller V6 in it. Ran great, but burned fuel heavily when lots of people were on board. We upgraded to a Crownline 202 BR with a carb 7.4L. To our surprise, we burned significantly less fuel, since the engine was less taxed.
In short, if you've got the cash, I'd say grab the 496, it is unlikely you will ever regret it. However, the 6.2L is a completely serviceable engine, and as far as we're concerned, you can't go wrong with a Crownline.
Todd - 4MM Gravois Arm, LoO
2000 266 BR 7.4L MPI BIII
"A-TEAM"