Ditto - I used to play almost exclusively at £25NL and found that whenever I played $25 instead I just couldn't take it seriously. Now play a mix of $25, £25 and $50 and seem to be able to cope with all equally. But it took a while and sometimes I still revert to donkishness at $25 (I lost a buyin Sunday, in the middle of a decent weekend's play, when I joined Party in an impatient mood and called every hand).