I don't think it's necessary. For me, an F1X is only necessary if I want to biamp, although there are some aspects of the sound that I prefer to the F2B. So, one of those with an SF2 should give you a full experience. For the old school Phil tone, I recommend an F2B, SF2, a Crest CA9 and a bunch of JBL 15s in the appropriate cabinets. For an 80s and on tone, then the SWR front end with Meyer cabinets might be a good way to go.
For me these days, it's the former rig, sometimes with Euphonic Audio speakers.
Also, if you go with a Series I or II, the F2B is probably the way to go, so each pickup can have it's own channel.