That's pretty much exactly what my dealer quoted me back in August.
Is the new ECU necessary? Honda says so, and that's all that matters. If you're going to get it from Honda, you're going to get a new ECU, period.
According to my dealer, the only way you'll get a unit from Honda is if they're paying part of the freight. If it's 100% customer pay, Honda won't sell the dealer the transmission.
Based on my less than satisfactory experience at what has otherwise been (for 25 years) a stellar dealership service department, I would recommend you call American Honda directly and open a case with them. I did not; I stuck with my dealer, and their route--through their zone rep--was less than satisfactory for me. I got only 50% accommodation from Honda. I suspect the zone guy is paid based on how well he fends these things off. Previously, American Honda was very liberal with fixing their screwups; now, according to everyone I've spoken with, they've swung overly miserly in their goodwill accommodations. Too miserly.
But I've seen some stories here where going directly to American Honda and opening a case got better results than my going through my otherwise (or previously) stellar dealer.
The dealership does the swap, and mine with with absolutely no hassle whatsoever.
See my previous posting here on the subject. Honda has lost my business completely, from here on out. They took a 25 year relationship that got them a bunch of sales and got their dealer's service department a bunch of business, and chose to act in such a way as to dump it completely down the toilet. Their handling of the five speed transmission issue has turned them into nothing more than what GM and Ford were at their worst.