Hi
This is a classic dilemma of most MBA (Finance) graduates. Financial products can be best marketed by people who have have a fair understanding of finance and financial products and who can understand and explain the numerous queries posed by prospective clients who obviously would be finance professionals. So there is a huge potential for finance professionals to make a mark as marketing professionals of financial products. Yet most finance professionals, especially MBA -Finance graduates look at it as a weakness if they get into marketing profile.
In your specific case you are keen to make core finance as your profession and to that end you are even pursuing your CFA. By taking the marketing profile you will gain a rare experience that you may never get again. You may also get good insights into the psychological make up of people, make good contacts with professionals and of course you wont be idle and you will be earning too. However, there is a danger that you will have to convincingly explain your choice of taking on a marketing profile when you try for a core finance profile. However, once you complete your CFA your degree will largely ensure that you move to core finance will be relatively smooth. It is also possible you may just enjoy the marketing profile and may want to grow in it.
You have to take a call on what is more important, focusing on clearing your CFA while taking on the available job or waiting for a core finance profile while pursuing your studies. You can also think differently and if you have some capital, use your analytical skills to invest in the stock markets. This will be a good test of your knowledge and confidence in your analytical abilities, help you gain core experience and hopefully you will also make decent returns.
Best Wishes