Each visa category has different eligibility criteria, requirements and restrictions. Whether you are eligible for the B-1 visa depends on the purpose of your trip. The B-1 visa is for business visitors, and there are limitations on the types of activities that you can engage in while in the US on a B-1. For instance, the B-1 does not authorize U.S. employment. If you are coming to the U.S. to work at your employer's US subsidiary company, that would be an improper use of the B-1.
If you are not eligible for the B-1, you can expedite the L-1A petition by requesting premium processing. With premium processing, USCIS will issue a decision on your case within 15 days. You then apply at a U.S. consulate/embassy in your home country to obtain a U.S. L-1A visa for entry. I recommend consulting an immigration attorney to determine your eligibility, and to identify the best option available given the time constraints.
Please note that this information does not constitute legal advice or create an attorney-client relationship.
The L-1A will be adjudicated according to the same standards either way.
What is risky is using the B-1 inappropriately - this visa does not allow you to work for the benefit of the U.S. entity. Unfortunately, the red tape is a necessary part of the process.
Get a qualified attorney to advise you to try to minimize delays.
Actually I would encourage you to take advantage of the B-1/B-2 visitor's visa category to conduct permissible business activities while you apply for the L-1 visa. Please remember that you must observe few facts: 1) you may not engage into gainful employment while on the B-1/B-2 visa status; 2) that you partake in activities consistent with the list of activities allowed in the regulations such as attending meetings, setting up operations, training, conducting independent research, etc; and 3) that you are completely transparent with the US consular officers at the time of the B-1/B-2 visa application and/or entry in the US.
I have counseled many clients to follow this plan successfully. Please consult with experienced immigration counsel.
Best of luck.
Gus M. Shihab.