I don't have experience of the Raymarine to compare but I upgraded last year from a Garmin handheld GPS to a 45DV with the DownVu transducer.
Not had it on the sea (just freshwater) yet but so far really pleased with its neat size, screen detail and menu operation. Really like the clever bracket so you can just unclip the unit from bracket/wiring in one motion when you leave the boat for a while.
Came from Barnet Marine NEW GARMIN EchoMap 45DV GPS Map Sounder Sonar Fish Finder INC Down Vu Transducer | eBay
If you phone them to buy on a card direct they will usually beat their Ebay price.
Beware if comparing other prices on the 45DV that you compare like for like... Barnet's price includes the better transducer and post but many quote with no transducer or the cheaper standard one.
Initially I screwed the base to the SIB seat but for this summer I'm making up a wooden bracket that takes the 45DV on top and has a battery box suspended under so it's all self contained and will be quick mount/dismount with straps or similar. Someone else on here (Karman?) has done this and it's a really useful setup.