At least, Erap had some "experience" as a public official before he became VP and P.  FPJ is totally devoid of any experience.  A person was ambush-interviewed and was asked about the FPJ run.  The answer was "Pwede ba mag-kagawad muna siya."
Recent survey by Pulse Asia (I think - there's so many "honest, reputable, survey firms 

 ) shows that Roco still leads the way, followed by the (Witch) King FPJ. BTW, that survey IIRC was limited only to Metro Manila.  According to recent reports, if GMA, Roco, Lacson run, GMA has a bit of an edge, with the Visayas giving her the boost.  If FPJ runs, he has Mindanao.
Funny thing about Roco is that I've heard the Bicolanos are not too happy about him.  I can see many Metro Manilenos - particularly the youth - would vote for Roco.  But, those at Bicol don't like him - which is telling, because he comes from that region.  According to a group of governors there, they do not support Roco.  One commented: "Ano ba ginawa ni Roco para sa Bicol?"  Obviously, the way he was talking, the answer was a "no."
I hear that the PCCI will be hosting a debate between Lacson, FPJ and Roco.  They want to know the economic platforms of these candidates.  I hope they show it on TV.
Lacson has already intimated that he doesn't want the VP.  It's still possible that FPJ might just withdraw for the presidential race and run as Lacson's VP.  Now THAT would be an almost impossible tandem to beat.  The strongest the admin can come up against that is a GMA-De Castro tandem.