I have been on board of SQ1 several times.
It was built for the Russian Navy (if you visit the bridge you can see that all instruments are in Russian- including a beautiful compass).
The boat is relatively big- space is not a problem. However, the diving platform is more or less the same size as most boats, so it is more or less the same "coziness" that you'll meet in other local boats. Water is not a problem neither- even for long trips at full capacity (I think they have a water maker).
Inside it is also quite similar to most boats that I've seen- probably most of the boats are outfitted with the same contractors/carpenters/etc and same workmanship so they tend to look quite familiar
They have two dinghies, but from my experience they are not in tip-top maintenance so ended up a few times with only one operational dinghy. For such a trip, and if in full capacity you have to insist on having two zodiacs in good condition.
Crew? I don't really know how the guides are in water, so can't comment on them other than they are friendly and do a good briefing before the dives.
Most of the crew have been working together for quite long time so they know their work and do it fine.
The cook is good as most boats I've been- tries to make the best of whatever ingredients they have.
Zodiac/dinghy drivers were really skillful and with superb seamanship- it is important when you rely on them at relatively high seas etc.
Dive Sites? Most boats go to the very same sites depending a little on sea conditions. Itineraries do not change much, and you'll probably have some flexibility to choose or variate dive sites upon request.
I am not sure if it is a good idea to dive Elphinstone from Sharm because of the long time consumption there&away, although there is a bright side: you'll have a "bonus" Ras Mohammad. If I remember correctly, SQ1 is the only boat (or one of the few) going to Elphinstone from Sharm. It will take you about 1-2 days getting there, and 1-2 coming back to Sharm, so for a 7 day trip it will leave you about 3 days to spend in Elphinstone area.
Perhaps you should check other options (like starting from Marsa Alam etc.) which are closer to Elphinston and other southern sites?
One more thing: diving with the Oceanic White Tip sharks in Elphinstone is a hell of an experience- especially if there aren't many boats and you get their full attention most of the time. These are none of the coward sharks like hammerheads that are afraid of their own shadow and shy away when you exhale bubbles. Oceanics tend to come and "investigate" you from very short distances. If you don't like sharks rubbing your fins or bumping into you camera's port then Elphinstone may not be the place for you
Enjoy, it is a great place!