How much gear did you find Pete? There are a few possible placements I saw, but it would still be a bold lead. Is there enough to stop the possibility of groundfall from every point on the route?
It's not my favourite style of climbing (no cracks) but even still I would expect to make it up a 5+ normally, particularly when just trying it on a top rope. I did Namula again on saturday and that seems like normal 5+ to me. I perhaps shouldn't compare Trad Rules to Keema as I only got this far on my onsight attempt at Keema: http://www.ukclimbing.com/images/dbpage.html?id=30726
before falling (my excuse is that I didn't have a cam big enough to protect the top so got scared and jumped whilst I still could - a poor excuse I know
next summer... next summer... ) but Keema felt much more 'doable' to me and that is given 6b in the guide, not 5+.
Luhti is a great crag - but people should take care as there is loose rock around still. We pulled a large block off "Pienenlainen pettymys". Helmets are probably a good idea, particularly for the belayer.