Either one is good. I think they are below $250. 125L is about $199.

Nothing wrong buying in big box store. You can get a bad dealer also. At least in box store, if you change your mind and want to get refund, no question ask in 30 days. Try this with the dealers!!! Don't count on dealer honor your warrantee either, they might not and they charge you an arm or a leg for repairs!!! You are looking at the low end stuff, one repair can cost over half of the trimmer. Go for the cheapest price, be it a dealer or box store or even online. Think dispossable.

IMHO, after over 20 years service out of that Stihl you will only get p.o'ed with the cheap box store disposables. Have a look at the Stihl FS45. If you want straight shaft the FS55L but make sure to get the Auto Cut C head. The standard head is a pain to load.
I have an older Echo GT curved shaft I am pleased with.

As I said, the two you mentioned are very good, can't go wrong with them. Here is a few that I consider are true commercial trimmers and are within your price range.

http://cgi.ebay.com/Kawasaki-Weed-Eater-Trimmer-KTF27A-New-String-Trimmer_W0QQitemZ280331730721QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item414512bf21&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

http://cgi.ebay.com/Kawasaki-KGT27B-Commercial-Line-Trimmer-NIB-254-99_W0QQitemZ220401330208QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3350f16820&_trksid=p3286.m20.l1116

http://www.amazon.com/Tanaka-Commercial-Straight-Compliant-TBC-240PFS/dp/B001P3O23C/ref=sr_1_2?ie=UTF8&s=hi&qid=1243748448&sr=8-2

Echo-SRM210-$200.00

SRM210 is very good and good price. I did not mention it because he might be disappointed going from a 27cc that he has for so long down to a 21cc engine.

Quality has gone down a lot on Stihl and Husky homeowner equipment these last few years, they still make good pro equipment. Steve

Going to a local dealer Monday to check out the Stihl and what ever else he has. I have ruled out husky.

Hi Guys: Went to the dealer and bought a Stihl FS56RC. I bought a straight shaft figuring I would use a saw blade also. It has the AutoCut C 25-2 head.
After using it for a few minutes I noticed I only had one line left on the head. The dealer said cut 2 12ft pieces of line, stick them in the holes and twist the knob to thread them in. Now for the dumb question, how do I get rid of the remaining piece of line. When I tap the button on the bottom It wont come loose. Thanks Mike

I sent a message but it didnt go through. I solved the problem and got it rewound. Thanks for the help. Mike