We used the EC-30W on our 2001 Adventurer with the Onan 5500 watt generator. If we didn't use the generator for an extended period of time it did need to be primed. However after it had been run for a while it started easily for a couple weeks without the prime. One nice feature of the auto start is that according to the manual it will only crank the starter for 15 seconds then give it a couple minute break to avoid overheating it.
I would start your generator in the usual manner, let it run for a while then shut it down. The next day I would try starting it without priming it. If you're successful the EC-30W should be able to start it without any problems.
Hikerdogs
2013 Winnebago Adventurer