As a 75 scholar, and a member of an avid salvage group, I'd like to share my experiences to help answer your question.
Assuming you aren't leveling scholar just for salvage, and you have other reasons by leveling it, by all means, do it. Scholar is a powerful job in salvage. On the lower floors, the stoneskin/phalanx/and enspells make you both nearly invincible and adds to the party's overall damage on mobs. Although scholar -can- be a cell-intensive job, It really pays off. Besides, if you are using a smaller, more experienced group, the cells should not be a problem. My group has 6 constant members for most NM's in salvage, and usually 7, maybe 8 if we focus on a boss run.
As far as not having haste... Yes, haste is important, however, for most big NMs, as well as bosses, It's usually wise to bring more than one mage anyhow. A red mage or whm will suffice and compliment the scholar very well.
Also, lets not forget the fact that scholar can be a pinch-hitter for nuking as well, which can be useful for several feats, such as QQ Astrologers, Magic bursting any skillchains done to speed up kills. (specifically, the gears in B. Remnants to gimp homing missile), and for those squishy flan, just to name a few.
If you are in a salvage group that will fail to see the advantages of having a scholar in salvage, perhaps you should educate them.
Our run normally consists of having the scholar take the first ability, magic, and subjob out of the chest. From there, It's all smoothly done.
As stated before, If you are leveling scholar for reasons other than salvage, by all means, do it, and reap the benefits in salvage. If you are just looking for a job that you plan on using in salvage, it may be more beneficial to level whm or rdm to fit the role a little better. It's all dependant on how you play, and what you enjoy.
Hope this little bit helps!
p.s. As for your sub question... You won't be gimp missing the sch relic. It's very nice as a whole, but you can function just fine without it. The key piece, IMHO though, is the body. Still, it's a luxery. You'll survive just fine without relic if you don't attend dynamis.
Edited, Aug 22nd 2009 3:21am by Duelmikauzero