Paddy Richter is for melody playing, normal Richter is for chords. It\s made for Irish music.
Paddy Richter tuning basically means you can play relatively easily over 2.5 octaves instead of 2 octaves. It just gives you that extra bit of range. Especially if you run a D harmonica, where the top notes are near impossible to play and don't sound pretty you need that bottom register to play at all. For a G harmonica you'll find that most tunes in Eminor are easy with Paddy Richter and awkward without.
Again though if I were to start over with playing harmonica I probably would've gone for the Sampler or a tremolo harmonica in soloist tuning (both are the same tuning) just look at the tuning here:
http://www.overblow.com/?menuid=26#67Compared to:
http://www.overblow.com/?menuid=26#57Soloist tuning is much more consistent over the octaves, every octave is played the same while on a paddy richter the note direction changes on the upper octave and on the bottom octave you need to bend to get all the notes.
Another thing, Irish music has a much richer history on tremolo harmonica's than bluesharps.