generally I keep the PMR at the legal 0.5W which gives more than enough range while on the move, though the radio I have I can up the wattage to 2W with just a couple of key presses and it's came in handy on a couple occassions,
for example out for a scoot rain came down pretty hard one of our party started to fallback and the front runners where moving on so I up't the radio to 2W so all partys could hear me to let the front runners know I was pulling in to let the those that had fallen back catch up and make sure they were okay, the downside is the other partys couldn't return the calls as they where out of range for there radio's, so having a radio that can do this does have it's use's
the downside to uping the power is reduced battery life the more you increase the power the less battery life will be.
regarding getting your collar felt, is pretty slim as mentioned the PMR band is pretty much left alone, you'd need to be very unlucky to get caught.
you can do somethings to help yourself, having a remote aerial may look good and give good reception but it's illegal to have a remote aerial on a PMR radio in the UK so this is an obvious sign your doing wrong also try and pick a radio thats not obvious you have increased the power (IE big bright LED next to the high power symbol
)
As far as interfering with other users it'll only be other PMR users you'll interfere with but again using the channels and sub-channels you'd need to be unlucky to be in range of someone else with the same channel/sub-channel and even then you'll be out of there range quickly, in the couple of years I've been using radio's on the bike it's only happened once where we ended up on the same channel, you do pick up chatter passing large shopping complex's but they don't interefere with your comms if you use a sub-channel
The long and short of it, it's handy to have a radio that can increase power quickly and the chance's of getting your collar felt are very slim
HTH
