Your basic procedure is sound. Unlike an installation on a PC, an installation on a Mac doesn't render the computer dependent upon the Linux partitions to boot. In a worst-case scenario, you could hold down the Command key while booting to select OS X. You might want to uninstall rEFIt unless you plan to install Windows or have multiple OS X versions running on the computer.
One comment: Your hybrid MBR is odd at best, corrupt at worst. Specifically, it's got two 0xEE partitions. Some versions of the Ubuntu installer tend to create this type of setup, which often causes problems. I'm not sure how Disk Utility will react to it. At best, it'll fix it automatically when you delete the Linux partitions. At worst, it'll flake out and corrupt your disk. Thus, I recommend you take care of this before you do anything else. It's possible that Apple's gpt utility has an option to write a fresh protective MBR, but if so I don't know what the option is. My own GPT fdisk (gdisk) utility can do the job. You can download a copy from its Sourceforge download page, then use the "n" option on the experts' menu:
The "x" command enters expert mode, "n" creates a new protective MBR, "o" displays the MBR data (so you can verify you've done what you expected to do), and "w" saves your changes. With this done, there'll be no chance that unusual MBR data will confuse a GPT-aware partitioning tool.
$ sudo gdisk /dev/disk0
GPT fdisk (gdisk) version 0.6.14
Partition table scan:
BSD: not present
APM: not present
Found valid GPT with hybrid MBR; using GPT.
Command (? for help): x
Expert command (? for help): n
Expert command (? for help): o
MBR disk identifier: 0x00000000
Number Boot Start (sector) Length (sectors) Type
1 1 3981311 0xEE
Disk size is 3981312 sectors (1.9 GiB)
Expert command (? for help): w
Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
Do you want to proceed, possibly destroying your data? (Y/N): y
OK; writing new GUID partition table (GPT).
The operation has completed successfully.