I don' think I've ever had such a $ vs. convenience conundrum, honestly.
I just know in my gut after reading dozens of opinions from those that have used BOTH, that the omni is unquestionably easier to use/live with, but at the same time, if you're spending much more than $100 to use REW/HOLM I think you're doing something wrong, so a ~$200 savings is nothing to sneeze at.
Worst fear: I'll use EITHER of them a handful of times in the first few months and then that will pretty much be the end of it. You can only measure the same room and equipment so many times, and I'm not one to be switching out my gear nearly as often as so many others. THEN, it's $100 vs $300 all over again, lol.
I'll TRY to make up my mind in the next few days, lol. Since measuring equipment doesn't seem to be planning on making any quantum leaps in the near future, the nice thing is that you can be set a good long while with either...so another point for omni over the long haul with it's ease of use and speed.