Well rjb84, I can say from commentary on this site that a lot of people really prefer Maris Otter. Having just started my first AG brew using it, I can't provide a lot of feedback myself, but it's just a higher quality base malt. As far as I could tell the cost difference was negligible, so I'd say go for it if you can.
I'm wondering something else on the topic of flavoring with nuts. What if you used something like a pecan syrup - perhaps something you'd use to flavor coffees or pies with? I'd assume it'd be mostly fermentable, probably just leaving behind the extracts used to provide the flavor, while not leaving any oils to worry about.
I'm mentally preparing myself for a "hazelnut coffee ale" and am trying to figure out the same issue with hazelnuts. I just can't imagine soaking them in hot water for an hour is really going to extract much flavor.
Thoughts?