Not much different to use an IP device than an RS-232 device. Set a static IP for the Symetrix; add the driver to your project and fill out the IP address in the properties, and you should be off and running. You can probably get a good deal of help on RTI and IP drivers at the RTI forums too.

That being said, if you're more comfortable using RS-232 and the Soloist piece -- and especially if Symetrix can't provide any support at all for their own driver -- it might not be a bad call going that direction. At least if the driver doesn't work reliably you can manually enter the RS-232 codes you need.