Dealing Desk Broker ok for Long Term Manual Trading?

Hi there obviously we have all read and heard about how Dealing Desk brokers are inherintely in a conflict of interest, and how some of the less reputable brokers will manipulate prices to their advantage.

This has a negative effect on scalpers but how about more long term manual trading. If I am trading from the Daily charts and most of my trades will last days/weeks, do I still have any reason to be concerned with the downsides of DD brokers?

For those of you that have experience with both which do you prefer for this type of trading. I am debating on whether to go with Alpari or MB Trading.

Thanks in advance for any help.