I learnt with PADI in Guernsey in the mid 90's, the class room stuff was a lot more intensive then and the confined water was done in a pool before we were even allowed in the sea. I then did about 30 dives in Guernsey waters in some pretty crappy conditions. I did my Advanced in the Red Sea in 98 and found it really easy to complete, mainly because of the experience I had gained in cold water with crap viz and strong currents.
In 2004 with 100 dives done I did my Rescue diver in Barbados and then moved to the BVI where I did my Divemaster and did 3 years of diving pretty much every weekend.
I have led countless dives with newly qualified and well taught PADI open water divers and also with experienced divers. Nearly all tourists just wanting to see the reefs and wrecks. Newly qualified PADI divers don't have the experience of a newly qualified BSAC Diver you can get your ticket after 8 dives with PADI, that certifies you to dive unguided to 18m, you can also rent your own equipment and take yourself off diving whereever you are in the world.
Personally I don't think thats enough. You don't build enough experience and you certainly don't have the knowledge that a BSAC diver would have accrued in his training. If I had to rewrite the PADI course I would lump open water,advanced open water and Rescue Diver all together.
However,as I said before, if you're only going to dive with an experienced guide in warm water, in good viz then PADI is perfectly acceptable. If you plan on diving in any other circumstances then go the BSAC route.