check6, you never said which model Echo you have, but if it's a smaller model and you want to upgrade to a mid-size pro Stihl, I'd suggest the MS-261 with 18" bar. It has a magnesium case and weighs 11.5 lbs. It is 50cc, but will easily out cut the larger (and heavier) 55cc Farm Boss and use less fuel to boot (all due to improved technology/capability).
An equivalent pro Husky saw would be the 346XP. It's a very good saw. And the comparable Echo would be the CS-500P. The MS-261, 346XP, and 500P are some of the best saws from each company.
You're likely to get recommendations for the Stihl MS-250 and MS-290 (Farm Boss), but you're better off putting your money into a higher end Stihl. The 250/290 are plastic saws running old technology and weigh more than they need to. They are Stihl's best sellers, but that's mainly due to price point.
I wouldn't worry about the Stihl flippy caps. They have worked out the kinks at this point, and the caps are pretty easy to use. I would suggest you pay attention to the little black notch though, which shows you where to insert the cap before tightening back down. People run into issues with the flippy cap when the notch gets out of phase with the hole and rotates the inner sealing toggle. Fixing that is a simple matter of rotating the toggle 180 degrees to "reset" the cap, but it really trips up a lot of people.
Now, the fact that I need to explain that is a reason to think the flippy caps are a dumb idea. I mean, it's a cap, and it should be working for us, not the other way around. Personally, I never had issues with a regular screw cap, and would prefer them if given the choice.