[JaggedNZ]

I've had great success with Postgres FTS for some complex (i.e large, non-standard, highly specialised corpus) and basic search (very small corpus) features.

Prior to switching to Postgres FTS had to maintain a seperate FTS applications index. I would say make sure that the gain of using a seperate FTS engine outweighs the maintenance cost, given that maintaining a FTS index in Postgres can be very minimal if configured correctly.