the only small undergroundy legal thing i go to is Project Storm in Oxford.. the attendance has slowly increased throughout the year, it was pretty mcuh empty when i first went in March or round bout then - when i played there last month it was fully ramed.
i would put it down to building up a reputation over each event, which must have been 8-10 or so - fair play to 'em , it's a banging night :)
i'm getting into the smaller nights more - been to Addict's night Resonate, and i'll be at Oblivion a lot in the future ;) . but ya cant beat a good old 12-16 hour party, which the smaller nights just cant offer, and i go for them the marjority of the time.

i'd like there to be more small parties, but there is a serious lack of affordable venues in south bucks (hell i'd been doing it if i could find one).. i dont like to have to travel more then 40 mins if a night finnishes at 2/3am - it's all cheese gayrage & RnB in the venues that would be suitable , but theys do not want crusty partiers in their posh bars n clubs..
there is the market for it, i know it would take a few parties to get established, that's a given - times are a changing, i think folks are now wanting to get back to the roots, forget the commercialism of super clubs and get down and dirty with promoters and DJs who care about the scene and music rather then getting £15/20 out of them for super star DJs' wages - OK things like big "Weekenders" are getting more popular i think, but they are a more special time and bit of an adventure....
dare i say there is a general trend shift towards the harder side of dance music going on at the moment?
anyway, i waffle on... too much herb, thinking head on ;)