In a twin, the OEI Escape manoeuvre/emergency turn procedure is calculated to ensure obstacle clearance at all available weights for the aircraft up to the maximum weight/temperature combination on that particular RTOW chart - ie to ensure obstacle clearance at each of those weight/temperature combinations.
It doesnt matter a whit whether you're IMC or VMC - with proper average piloting technique (and without using TOGA thrust) you will clear the obstacle(s) that limit the takeoff. (it also helps to get the gear up!!) If taking off with Reduced/Flex thrust, going to TOGA will provide an additional level of obstacle clearance but is not mandatory in order to clear the obstacle.
If some pilots imagine that in VMC they are going to construct their own escape manoeuvre and visually keep themselves away from terrain they are sadly mistaken, and I hope I'm never in the back of their aircraft in a limiting takeoff with OEI. As someone said earlier, all that will do is to ensure you see the mountain get bigger in the windscreen.
However, IMHO, you should always tell ATC exactly what your company ETP is, as they will probably not have it to hand even if your airline is one that informs ATC of such manoeuvres. At least that way they can work in advance to clear other traffic out of your path.
Another point worth mentioning is that an ETP for takeoff is not necessarily required for the go-around case due to different points of application of TOGA thrust and different heights for that application (CAT 1 200 vs zero feet on the ground plus the fact that the go-around is initiated at a point further back (from the obstacle). The baulked landing is a different case and may be required for places such as Innsbruck in Austria.
If an ETP is required for the G/A case it should be stated in your performance/Ops manual. In any case it is up to each company but especially each pilot, to ensure he's up to speed on the exact details of his company's procedures.
Additionally, you should ensure that you fully understand the basis on which the ETP is constructed. Is it based on continuing to keep the aircraft climbing at between V2 and V2 + 10 in the climb/turn, or is it one of those (rare) procedures that allow you to level off at the usual single-engine acceleration altitude and simply turn as directed ( much wider radius of turn bringing more distant obstacles into play and thus limiting the takeoff weight even more).
In my experience, most ET procedures involve CLIMBING turns where there is no level off until the turn is complete. However, I believe a handful of airlines do use the other type which will usually be far more limiting on the available weight that can be lifted.
In every case:
1. Know your own company's procedures
2. Apply them in all conditions - VMC or IMC
3. Don't attempt to second-guess the performance engineers who constructed the engine-out procedure in the cold light of day using the aircraft manufacturer's performance programme.
It might just keep you (and me) alive one day.