You mention a double chin and neck fullness. Your best approach is to consult a board certified plastic surgeon in your area, have an examination that allows the surgeon to assess your needs and desires, and makes recommendations. Consider meeting several surgeons to finalize your decision.
Liposuction is appropriate for under chin and neck fat in patients who have good skin tone. This means the skin may tighten and reshape after fat removal.
Lifestyle Lift results would depend on the skill and experience of the individual surgeon, rather than the brand name or corporate website examples. Their marketing program may direct you to a specific plastic surgeon who could perform the full consultation process I mentioned above.
With a double chin, what you need is to see a surgeon who specializes in face and neck rejuvenation who can determine the most reasonable method of achieving the result that you wish. Since you are older than 46, it is extremely likely that liposuction alone will not correct your neck. You will probably have significant banding and loose skin left after just that procedure. If this is the case, you will need a full facelift, which the lifestyle lift states in the fine print that it is not. Therefore, seek a plastic surgeon with significant experience in facial and neck rejuvenation. Remember also that you are dealing with your face and that you usually get what you pay for.