Sellener,
This is just my $.02,
The information supplied to you so far is pretty accurate; I was in a 141 environment after doing my private under part 61. 141 can get it done faster, but it can also be much more expensive per hour than 61. That being said, I believe the 141 environment is often, but nowhere near always, an environment more geared to pilots with a desire to fly professionally.
If you decide to go 61, and have any desire to be a CFI, then consider the following:
You have 150 hours until you are even qualified to take your checkride. Why not take this time to transition to the right seat of the airplane? This will allow you to get fully prepared to fly the maneuvers from the instructor's station...If you can talk through maneuvers well and explain your actions in real time, your commercial checkride will seem only a little different than a typical CFI practical. This means that coming out of your commercial checkride, you will already have the physical skills necessary to fly the tasks to PTS. If you train this way, your focus following your comm/sel would then be honing your communication skills, broadening your knowledge base, and (if you haven't already by this time) putting together lesson plans.
Why spend 10-20 more hours of dual for your CFI when you can train through the maneuvers as a commercial applicant?
Since your question was pretty much answered above, I figured I'd throw this into the pile. I'm not advocating taking your CFI the day after your commercial...I'm basically just saying that by doing your whole commercial from the right side starting now (for the rest of your 150 hrs), you won't have to do anywhere near as much work in the air for the next ticket. Could save $1000s if done correctly and taken seriously.