Are you describing some sort of prefab grip heater, or something completely homemade?
Here is my opinion:
Pro: easy to install
Pro: clean looking install
Pro: Warmer (hot)
Con: you must choose one of two grip styles
Con: hard to change after the fact -- you can break them on removal if they are stuck on too well.
Con: does not come with a relay so can accidentally be left on.
Symtec (adheres under grip):
Pro: choose whatever grip you prefer
Pro: choose whatever wiring and switch/"dimmer" you prefer
Pro: depending on your install method, worn grips can be replaced later.
Pro/Con: install is as clean or messy as you make it
Con: not as warm as Oxfords
Con: tend to loosen up after a time (i.e. over a year)
I have used both Oxfords and Symtec heaters. For myself, I prefer Symtec as I like to choose specific grips with anti vibration properties. I have had several sets on several bikes. My girlfriend has Oxfords and they are basically plug and play. They are also very warm!. That said, as they come out of the box, they due not include an electrical relay so do not turn off with the ignition. While they are supposed to turn off when the battery charge is down. With the Symecs I use a relay so they are definitely off when the ignition is off. You could add a relay to the Oxfords, but this is no longer plug and play.
Warmnsafe sells a symtec kit which includes their heat-troller -- variable heat instead of high/low switch.
Either way, to do the job properly, by the time you are done, the price difference shouldn't be too much if you have factored in make a proper wiring harness for the Symtecs, or buying someone else's wire harners. Eastern Beaver used to sell one but no more