Visibility is excellent from the lower helm. *I do have trim tabs on mine and use them. *They do improve the view over the bow. * I see your asking questions in the general area too, but I'll add my 2 cents here. *This is strictly my opinion as I have not been aboard a Cat powered 34LRC, *Mine has Tw. 200 Perkins, *It will do about 20 mph (statute) at wot. *That is with full fuel and water tanks. *Cruise at about, 16 kts. *From what I have read, the 210hp V8 Cats are a little slower, but not much. They are a lot BIGGER physically than, and heavier than the 6 Cyl Perkins. *The extra weight is responsible for them being slightly slower. *Because of their width, they make the engine room tighter. *Particularly if you need to access the far side of the engines. *There is a common opinion that the Cats are a 'throw away' engine because they don't have cylinder liners. *That I think is unfair, they are very durable. *Parts for the Cat are far more available, and cheaper than the Perkins. *They don't have British threads,which are a PIA to find. *Non marine parts sre very available in the truck parts channels. *Perkins non marine parts can be found in the Massey Fergusson Tractor world, but not he heat exchanger parts.
You said you wanted two cabins for sleeping. *The mid cabin to port in the 34LRC is very tight for space. *And for that matter the v berth isn't too big either. *The 34 has a lot going for it, but sleep accomodations are not at the top of the list.
I didn't buy my boat for the engines, I bought it for the rest of the boat.