The raindrip couplers are designed to stay in. I just cut about a foot a way and add a connector if you are going to keep the corner, if not then cut on either side and add whatever connector you need. The needle nose plier did not really work for me. I got a serated knife and split the tubing inside the coupler. It took a while but eventually I was able to cut it out.
Raindrip is patented to only work with raindrip parts. The tubing is not compatible with most other systems.
I know this from experience. When I wanted to extend my raindrip system, the local hardware store stopped selling it and I had to get an end fitting and connect the other brand of tubing to it with a hose bib connector fitting.
Drip mist, and Robert's tubing is compatible. Robert's tubing is generic from my local sprinker supply and it can also accommodate risers and regular sprinkler heads which I use for grass and shrub borders. If you keep uncoupling those, you will have to use hose clamps especially if you have high water pressure and you are not using a pressure regulator.
Netafilm is also only compatible with itself. Hydrotape is only good for a single season and only if you plant in rows so I have never used it.
I have used drip systems for over 30 years because of their versatility and I can put on soakers, sprinklers and even drippers on the trees as long as I have enough zones and pressure. I did pay a landscape company to put in a manifold and six zone timer and 2 zones are grass zones with standard pvc. and 4 zones are drip. The system that is the oldest is the raindrip and it the main lines are starting to deteriorate so I will probably replace them. Lowe's is carrying raindrip again so I can get parts again but I may replace it with Robert's tubing instead. Emitters are interchangeable no matter what system you use but main lines and connectors are not unless you are using beginnings and ends.
I prefer the drip system since I can move it out of the way when I am working in the area, and I hate it when I hit the pvc pipe and have to repair it. I can change the riser heights and I can use low volume heads, shrubblers, vortex, misters, multi heads for soakers, or standard heads on the drip system. I have had to replace parts of the system I accidentally hit or disconnected when I moved it, and replaced a lot of lost and clogged emitters. For this I have a couple of buckets of spare parts and tubing. It is a little harder to change heads on an underground system.
At my community garden timers are not allowed but I have set up my three beds with drip sprinklers and shut off valves so I can work in one area and water the others at the same time. Lately, it has been raining most of the time so the sprinklers are off.