We have expertise on socialengine and have been working on it since socialengine 2.x(~4 yrs). We offer end-to-end SocialEngine expertise, including consultancy, implementation, customization, migration from older versions of SocialEngine and performance tuning. We have recently done migration from socialengine 2.x to 4.x so we know whole socialengine throughout.
One of our clients have ~125K Page Impressions per week and growing.
Here are few applications that we have been working recently :
Social Kidspot - Community for Mothers
Share My Guitar - Community for Guitarists