I have alot of boulders edging my grass in North Carolina. I am a homeowner and looking for the best recommendations b/w $150 and $250 for a great gas trimmer that will give me the least head aches. Because of the extensive rocks and boulders used as edging on my lawn I have had so many problems with trimmers. The thick lines break or I have to keep re-threading the spool when it runs out. OR I have used the gator type inserts and they seem to break far too often. I am at a loss as if it is just a bad trimmer I have or the line. So I am this year going to buy all anew and want some advice. I just want to run the trimmer and not have to rethread anything more than once a month or so. Thank you!