With my situation I feel I have the best of all worlds, if the winds are high enough (which is not very often around here unfortunately) I can just tilt the motors up and sail. The extra weight of the motors doesn't affect the performance of the TI in any way. Many times we have 3-4 people on the boat and it performs just fine, adding the 60 or so lbs to the boat from two motors doesn't change much of anything. Since the weight is in the back, this also helps keep the bow up and out of the water, even if I didn't have the motors, I would likely add ballast weight back there anyway. The mast on the TI is mounted so far forward you need something back there especially if you are just running solo from the front seat, as the boat is more or less designed around running around with two passengers one in front and one in back, when running solo, this knocks the balance off a bit.
Personally I like having the ability to adapt to whatever conditions are out there, and still have a good time and be able to move along at a speed that is acceptable to me (even in very low winds). The problem I have is if it's a hot day and sunny(most of the year here) if your out on the water with no breeze to cool you down, it's like sitting in a frying pan (and I'm the yoke (LOL)). I still pedal 100% of the time regardless of the conditions, as I consider the TI to be a pedal boat, and you need to pedal to maximize the boats efficiency (plus its a great exercise program as well for me). If I want to go up to Egmont Key (about 20 miles north) and just hang out or go snorkeling, we just go. Often times we like to just bar hop where we might venture down south and stop for lunch at Sharkys then come back. For us this is fun. I don't have to worry about if the wind is going to die, or having to tack one direction or the other (I don't tack, no need since I can sail almost directly into the wind (probably the best point of sail on my boat). The inter-coastal in narrow and mostly you have to go either north or south to get anywhere, if the winds are from north or south (which is most of the time), then every trip would be a breeze one way but a nightmare the other. This is why my boat is rigged the way I have it, I can sail efficiently regardless of the wind conditions and direction.
I do carry extra gas on board (2 gallon cans, one in the front storage in a sealed container, and another in a bag stored on the rear deck, total weight about 12 lbs). This gives me the possible range of way over a hundred miles, fact is most days I only end up using about 1/3 of a tank of fuel from each tank (each tank hold 1/3 gallon). I measure my fuel after each outing. Basically I can go out all day and have fun for under a dollar in fuel. My hybrid system is so efficient, I can't remember the last time I ran out of gas out on the water and had to add more fuel on the water. The engines when running just above idle are extremely quiet, and with no sails up propel the boat to 6-7 mph just by themselves. Then when I start pedaling and open up the sails the speed increases. By reading the sails and working them effectively I am able to average nice speeds, at the very least fast enough to keep me moving, and a breeze on my face. I don't have to worry too much about the actual wind direction, or even if there is not much wind at all (which is most of the time around here).
Of course if it's a nice windy day, I just tilt one or both motors up and don't use them that day if I don't need them. But they are always there and ready just in case conditions change, or something else breaks down, they will always get me home. I've had motors on my TI for the last 4 yrs, and don't think I have ever gone out without a motor mounted on the boat since the first time I went out on the first day I had the boat ( April 2010) and my wife and I were stranded offshore for hours when the wind died, and the tide was going out, I vowed to never get caught like that again.