Thank you all for the very helpful replies.
Next question: Which external antenna is more widely used with the Sennheiser receivers? They make an omni and a directional--both passive devices (unless you need to drive a long run, then you add their RF amplifier). Either can fit on a standard mic stand. Most of my gigs are on moderate size stages indoors, but I do work outside on occasion, and every now and then I have to cover fairly good-sized rooms (100+ feet deep) with handhelds working audience commentary duty. My sales rep is pushing me towards the omni, but many/most wireless rigs I've seen are using directional paddle antennas.
I honestly don't thinks it's going to make a huge difference either way, since the directional antennas only have 3dB of gain. I'm just curious to hear what others are using and why.
Thanks.