The "bigger, expensive stuff" is not only not declining, it is flourishing.
A lot of guys at my clubs field fly electrics and Parkflyers, BUT the number of 100+ inchers is definitly NOT on the decline!!! Sometimes I don't even bring out my 60 sized planes because so many "big" guys are around and my 60 seems small.......Not to mention that nothing flies like a 120"r. One member had a 120"+ extra with a DA 150 twin in it, and it flew soooo realistically. Looked as real as they can get......