I'm trying to decide between the merlin system and a zacuto shoulder mount. What's everyone else finding good results with? Would merlin be a more sound investment, I had one before but only really used it for a short project, so I didn't use it alot.
Asking between a shoulder rig and a steadicam is like asking between a dolly and a jib. They are both different tools that give you different looks. If you can only afford one, then decide what style shots you want. Shoulder rigs give a smooth handheld look, but also allow for easily controlled focus. Steadicams allow for very smooth, floating shots, but require you to set your focus and go.
Fwiw, I got a glidecam 1000 pro and made my own shoulder rig and grand total for both was about $110. It's amazing what eBay and google can get you if you look hard enough.
It definitely depends on what you are shooting and how professional your gear needs to be. If you are shooting a wedding, you could use a glidecam handheld or with a vest/arm for many different beauty shots with a very wide lens so you don't have to worry about focus. At a reception, you may want to go for a more shoulder mounted rig if thats your style. If you are shooting your kids running around in the backyard and you like to build things, then DIY. If you have gigs you get paid at then get something that looks more professional and reliable. I use redrock rigs and like them a lot. If you are using a DSLR the eyespy balance is pretty sweet because it has counter weights which really help balance the front heavy DSLR. Their stuff is modular (like zacuto, cinvevate, and others) and priced very well. Figure out what is going to work for the shooting you are doing and buy it. Support gear will outlast your camera so keep that in mind. Good luck!