I would probably go with the newer Seaborne ship.. It is larger and it is newer and therefore I think it would be better..I have not sailed on the newer Seaborne ships but have sailed with Seaborne and I have sailed with Silver sea. I also sail frequently with Crystal.
There is smoking on the ships but we were not bothered by it.
Food will be great along with service. You will see the difference based on the price.
Thanks for the comparison, but Silversea does have a fairly new ship, Silver Spirit, that is slightly larger than Seabourn Odyssey and has more suites onboard.
Seabourn has almost all standard balcony cabins with maybe just about eight or 10 suites (they are all called 'suites' of course). I only say that to draw a distinction between the "type of cruiser" you might find on either brand.
You could say Seabourn is less stuffy - if you get my drift.
Actually you have two different options with Seabourn: The smaller Seabourn Pride (about 200 guests) and the larger Seabourn Sojourn (about 450 guests). The Pride tends to have longer 12 day cruises and the Sojourn shorter 7 day cruises.
The big reason I would select Seabourn over Silversea (not that Silversea is a bad product) is that Seabourn is fanatical about consistency of its service and cuisine not only from cruise to cruise, but ship to ship. Silversea has admitted issues with each ship being different and there being consistency issues between cruises.
Silversea's Cloud and Whisper are also two different ships, but keep in mind that the Cloud hasn't been "buffed up" in a while.
If you are looking for what I believe to be the most luxurious (but not over the top) cruise ship in the world, the Seabourn Sojourn fits that bill.
If you want to avoid stuffy or formal atmospheres, Silversea is known for being more formal and restrained. While you can have formality on Seabourn, the fact is that you can avoid it as easily as engage it.