Did some research into this, ‘wot I learned’ (camera newbie though, so take with a pinch of salt):
G10 – The most DSR like in size and handling. Has an EVF, but not as good quality EVF as G1 or 2, or the optional (but expensive) EVF for the PENS
PEN – Differences across range, but smaller and lighter than the G10 and IQ as good/better. No EVF.
LX5 (and similar) – Truly compact, unlike the others, can fit in a shirt pocket. Smaller sensor means longer DOF, so less scope for blurring foreground/background. Less flexibility in terms of lenses and ‘serious’ photography, but significant advantages in terms of portability.
Just IMO of course. I was after my first ‘serious’ camera, but one that I would actually use as opposed to leaving at home, so went for a (cheaper) PEN. M43 standard looks like it will be around for a while, so I will be happy buying another lens or two if I get serious.