These numbers sometimes confuse the heck out of me but pretty sure the FS-55 has the same engine as your blower.

Stihl/Echo oil mixes are interchangable.

Off hand I don't know what size line either come with but your mile of .080 will be fine in both. Unless doing heavy clearing .080 is in my opinion the best compromise between durability and good trimming. The heavier the line the more ragged the finish cut.

Warranty is subjective. Except for ignition coils, the vast majority of covered warranty will happen in the first 5 hours of operation. As for the coils, they both have extended warranties on them.

Both machines come with .095 but as nv says .080 will give a better cut in grass. You will find the Echo is smoother and quieter but not as much power as the Stihl although it will do a fine job.IMHO, the Echo is a better machine.

Never heard the Echo but My Sthil FS 38 is anything but quiet. It's even louder than one of those 89 dollor weedeaters. I also had minor carb issues since new, not Sthils fault but the carb manufacturer(same carb manufacturer as the Echo too). Otherwise a fine machine and I would buy another.

I've had the echo srm-210 for a few years & it runs fine & starts easily. The soft handle is a good feature. It reduces vibration & carries easily at a good balance point.
The line advances easily & is easy to change.
The 50:1 mix with the stihl "good" semi-synth oil will work fine.
I always wear my earmuffs when I use it, but it's not as loud as the old red vibrating, so unbalanced that you need a strap to support it, and left your hands tingling when you were done monster that it replaced.
Nothing against stihl, but I like my echo. It is one of three echo machines I have & am happy with.

Since you're already running Stihl equipment, unless your Stihl dealer also sells Echo then I'd stick with Stihl for your new trimmer. It makes life easier to only have to deal with one shop for parts, accessories, etc.

Both machines are going to be plenty capable at trimming grass around the house, and should give you years of excellent service.

Echo SRM210 gets my nod. I have had one for a year now and it has been a great trimmer.

Well I ended up buying the stihl since I already have one. The dealer gave me a discount, and I must say this is very powerful trimmer. Blows away the poulan pro I replaced. I kind of like the .095 line since it edges my St. Augustine turf easier than the .080. Nothing beats a quality tool...

I purchased an Echo SRM-225 yesterday at HD and returned it today. The cut was not smooth and the handle just didn't feel right. I had an older Echo (5yrs) that was terrific. Purchased a Stihl FS 55R today. It appears to cut smoother and just feels better. Both machines used .095 line.

Don't tell me the new 225 is not the same as 211!!! I still see the old light grey color Echo, stock up!!!