There are others posting here that may be better informed than me, so hopefully they'll share their opinion as well, but my experiences as both a hobbyist and a dealer has taught me the following:
1. We dealer's usually represent specific brands, and products.
2. As should be expected, our recommendations are based on #1, subject to the client's budget.
3. Many dealer's can select the brands they represent, so #1 and #2 should not be interpreted as the dealer will sell and represent products they don't actually know much about just to make a dollar, BUT, there are many dealers, especially in Custom Install, that purchase through a Distributor, so for those dealers they only offer brands available to the Distributor.
4. #3 doesn't apply to all dealers, so caveat emptor should apply, especially when considering a large purchase.
5. When possible, you should demo the product in YOUR space, using your speakers, and equipment. If that's not possible, try to at least evaluate the product in a demo room, or other setup.
6. Never allow the cost of a product to determine its quality (although there is often a correlation). (Marantz is a good example, they have some quality processors that sell for less than half of most of the higher-end processors. There are others as well.)
7. Owners will almost always love whatever they just purchased, especially if they paid a lot for the product, and that will drive their public comments. That doesn't mean their comments have no value, or are wrong, only that they will likely be biased, and this is all the more reason buyers should evaluate the product themselves when possible.
8. Lastly, to some extent, we all have differences in hearing capabilities, which is why I rely on my own hearing.
All of that said, the MP40 is an excellent high quality product, as are several other high-end processors, including the Trinnov and Datasat brands. There are others as well. Also keep in mind that the audio quality is one reason to consider a product, usually the main reason, but features and function are a factors as well.
Answering your question more directly, I'll assume your dealer knows your setup (speakers, the room, and your personal preferences, etc.) and is making a recommendation based on that info and products they represent, like the MP40. I doubt any of us can tell you if it's "overkill" without knowing your current setup and what you are trying to accomplish. If you are trying to decide between a Lumagen purchase or an MP-40 purchase (unrelated in function, except for the switching capability), and want an opinion, you should comment on which is more important to you, audio or video, or are they of equal importance, and if video is more important, what type and size display do you have because that can influence a recommendation as well.
Disclosure: We sell all of the above, with exception to the MP-40 only because we placed a limit on the number of high-end processors we offer. I have now listened to the MP-40 in one demo and two private home theaters, so my comment regarding its quality is only based on those experiences.
Jim