I've been leveling with Biochem as my "crafting" crew skill of choice. I am currently ~280 (out of 400) and I've found the stims, medpacks, and implants to be very useful.
The only drawback I've been observing is that it can be hard to find things you want to craft "at level" when you get there, and you may not be able to find enough materials in the open world to keep yourself fully supplied. Although sending your companions on gathering missions can compensate for the material dropoff (i.e. if you're leveling very fast), it will cost both money and time. Snipers and Imperial Agents in general can be at a slight disadvantage because they don't get their next "real" companion until Alderaan.
Biochem has been a worthy and useful leveling skill thusfar. Even your normal "green" crafted items will be better than most of what you can buy from vendors.
Additional Note: Building your companion's affection means that they'll complete crew skills tasks faster and get better results. It's a fairly noticeable bonus at higher levels (250+/400).