I am about to make a purchase for a omni lav for my sennheiser G2 Wireless system. I was wonder if I should avoid the "red mark" Sanken Cos-11, is it too much reduction for simple location interviews?
I also was thinking of maybe just getting a sennheiser mic since it already has the right connector without have to do any customization. I would go for the sanken if enough folks felt it was worth it over the ME 2.
I think the Sanken is worth it if you really want to try to achieve the best sound possible. A lot of people who aren't terribly concerned with audio quality are happy with the sound they get with the ME2. But, if you want to go the extra mile, I think the COS11 is a great tool to have and worth the investment. Plus, the COS11 comes with a little rubber mount that allows you to hide the mic, and it also allows you to use it as a boundary microphone.
I wouldn't get the attenuated version for just regular interview work, the regular D version would be better. Also, the COS11 is sold pre-made with Sennheiser's locking mini-plug connector, so you don't need to solder it yourself.
These will effect both if you can actually ever HEAR the distinctions between these and more moderately priced lavs, such as those from Sony, AT, and others.
The "where do you live?" also might be important, since if you're asking about these kinds of issues, you don't have a lot of experience working with various models in practical situations. There's nothing wrong with that - but since you're in the early stages of your career, you've got to consider what happens if your life goals change and you have to sell off gear someday.
Specialist audio equipment at a high level has some residual value, but the higher priced and more exotic, the LESS chance you'll get your money out of it when you go to sell it someday.
Then again, if you're ABSOLUTELY sure you'll spend your career recording your own sound - these might be a great investment.
These are intangibles. But real issues. Just as a personal aside, I have a lot of nice audio gear that nowadays spends a lot of time on the shelf, because I'm at a place where a line item expense for an audio specialist who brings their own A-list gear is simpler than training others to use my stuff.
So whether I'd originally spent $200 or $400 for the mic sitting in the audio cabinet is irrelevant today. And actually, I might have been better off buying the less expensive option and investing the extra $200 in something else. That's easier to see nowadays than when I was young and just wanted the "top rated everything" - even if my skills and recording chain meant I fed that top quality mic head signal into a mediocre backend that took out some of the fidelity that the mic was capable of producing.
See the point? "Best" is always going to be a relative decision with a LOT more complexity than just how someone else rates something based on THEIR criteria on a board like this.
Good luck with your choice, whichever way you jump.