I've used it before.. considering you get:
- SAM10/DRG5: Ancient Circle (hate producing; minimal if not against dragons)
- SAM20/DRG10: Jump and Attack Bonus (free attack plus constant ATK+)
- SAM50/DRG25: Dragon Killer (good for certain BCNMs, missions, etc)
- SAM60/DRG30: Accuracy Bonus (good overall, since it's constant ACC+)
- SAM70/DRG35: High Jump (another free attack plus enmity-reducing; my advice - good for after a WS/SC if you pull hate)
An early Attack Bonus plus a "free" attack every 1.5 minutes at level 20 seemed to help me gain TP quite well, which is a bonus for SAM. At level 70, you can perform 3 Jump attacks in 3 minutes, if timed correctly / on average - considering you might wish to save High Jump for WS/SC. Coupled with Meditate and Store TP by that time, TP gain will be quite fast - which is a key element for most SAM.
Most people would argue that once you get to SAM30, to switch over to WAR. I personally say don't because you'd end up losing the constant Attack Bonus (and free attack) and end up gaining a enmity-producing ATK+/DEF- ability plus Defense Bonus (which Berserk negates anyway). Considering how much TP you may end up having when you skillchain, it's a good chance you could get hit after using Berserk > WS. Due to the DEF-, you can get hurt decently. You end up getting these abilities/traits for /WAR:
- SAM10/WAR5: Provoke (only good if back-up tanking, personally; SAM are more DD type and not well-fit to back-up tank until later levels)
- SAM20/WAR10: Defense Bonus (constant DEF+; only good if back-up tanking again)
- SAM30/WAR15: Berserk and Resist Virus (25% ATK+/DEF-; good for WS damage only; produces enmity and increases chance of being attacked after WS/SC; Resist Virus only good at later levels and/or when solo'ing)
- SAM50/WAR25: Double Attack and Defender (10% chance to hit twice - considering average G.Katana delay is 435 means roughly 8 attacks per minute, approx. 9 average if Double Attack kicks in; Defender only useful if back-up tanking - though negates Berserk)
- SAM60/WAR30: Attack Bonus (constant ATK+)
- SAM70/WAR35: Warcry and Resist Virus II (ATK+ ability that produces about as much enmity as Provoke; Resist Virus II only good when fighting Plague/Disease/etc inflicting enemies and/or when solo'ing)
I personally say it's up to you. I used SAM/DRG to get my SAM up to 37 for use as sub-job for DRG due to the constant ATK+ and the free attack. It actually ended up helping me hone both skills at the same time, in a manner of speaking. Gets you used to both jobs at the same time while leveling up both of them. But that is personal opinion and experience, so I know it varies from person to person.