I’m guessing you didn’t place the peg, so I assume the wall has been at least looked at before by climbers.
It entirely depends on the merits of the climb in my opinion. Peril associated with the risk of falling off is ‘better’ than peril associated with a hold falling off and taking you with it. One involves a careful assessment of one’s own ability the other involves a lucky/unlucky guess and some crossing of the fingers. What is justifiable is a purely personal thing but most folk won’t take much risk unless the route is really ‘good’.
I’d base my decision on honest answers to these questions:
Which way of climbing it will I enjoy most?
Which way is likely to see someone repeat and enjoy the route?
What visual/environmental impact will the cleaning/bolting have – does my experience and that of any repeaters justify the impact?
What is the crag/area ethic – does the line justify straying from this?
How will other climbers judge my approach?
Personally a large part of the appeal of doing new things is seeing them repeated by others and discussing the climbing afterwards. I don’t put time or effort into climbs I don’t think are worth repeating. If something is only just worth the effort for an FAist then it is almost certainly not worth the effort for a repeater. There are unlimited possibilities for these sorts of new climbs but they just strike me as pointless clutter in a guide which just serves to make the worthwhile stuff harder to find. Everyone has their own threshold on this and mine is doubtless way lower than others. I dare say what you are considering is pretty decent though or you wouldn’t be putting mental effort into it.
For me I’d rather have one or a few repeaters appreciate my route rather than a whole bunch of armchair critics approve of my style but nobody actually do the climb.
Bear in mind that ‘purity’ is not a simple concept in climbing and one type of ‘purity’ tends to preclude another. The ultimate purity is untouched/unclimbed. Climbing something covered in dirt and grass that you could have easily cleaned on abseil is in my opinion more contrived than climbing a cleaned line, purity of approach is reducing purity of experience.
Designer danger is a bad term as it implies that this approach is contrived when the alternatives are not. In fact whatever you do involves a level of design, right down to choice of line and cleaning. It all depends on the climbing but I don’t sign up to the idea that all bolted routes should have regulation spacing. Loads of routes benefit from runout sections and I find it sad when folk ruin these by adding extra bolts (the top groove on Urgent Action/The Thumb for instance used to a have a huge and totally safe runout which was an exciting and fitting finale to the route). That said there is a fine line between a well-considered runout and plain old bad bolting and it takes a deal of judgement to get it right.
