jogging strollers

So I have a double stroller Instep...I have put alot of miles on it this summer. Its a cheaper one so I have been looking for another one. And suggestions?
Also I have read that alot of jogging strollers have a locked front wheel (it doesn't turn) however I hate using mine with a locked wheel...I find it very hard to use and its annoying to turn corners so I have it set so the wheel moves instead. I was told it needs to be locked because it makes the stroller more stable and safe...is this true?
Thanks!