Personally I like bloop tubes. I've had one of Barry Nesom's since 2005. I agree that a tube will magnify errors in your hold, but if your hold is good a tube can reduce aiming errors. Tubes can affect the balance of the rifle. I have both 6in and 12in tubes. The 6in tube balances beautifully, the 12in did not. Even after being cut down to 8in it doesn't balance well.

A word of caution about borrowing a friend's tube, not all 1813 barrels are exactly the same diameter. Other tubes may vary more, but Barry bores the collar to be a very tight fit to the measurements given. If you buy a tube I'd recommend taking measurements in several different places.

Also make sure that you have a big enough foresight element. A rough rule of thumb is to increase the aprture by .1mm per inch of tube.