Well that is a hard question to ponder, Thanks for trusting enough in my abilities to ask me personally!
They are both very good units with cutting edge technologies in their own fields, that being said, comparing the two is difficult because the BL in my opinion is probably the best conventional OWB on the market, conventional's typically don't care what the quality of wood is going in the box, they don't care what the shape or size is either as they are updraft units. The BL is probably the most efficient of the conventional boilers on the market at this point. Perhaps I'm jumping the gun here a bit because a new product came out a few months ago that is very close to what I have been asking manufacturers to do for many years, a dry firebox boiler, only time will tell how it performs in the field. I would expect a savings of 10-30% by switching over to a G series unit as compared with either of those units, again only time in the field will tell the real story! As a service guy who specializes in proper service and install I like the G series better than any gasser that I have seen so far because of the ability to access any part of the boiler easily that needs service, but they do require service!
Along those lines, I would like to give those in the industry that have devoted a huge investment in time, effort and monies to bring new products to the market a big thumbs up. old technologies were nothing but a barrel in a barrel with a door and smoke pipe, any nit wit could build one in his shop effectively, today's technologies in the OWB industry have evolved into teams of research and development people, the folks who have invested are still in the game, those that have not are now closed, along with them being closed, the buyer now has nothing for a warranty and they have given a black eye to the entire industry.
Cando, I believe you bought your BL on my advice or at least considered it, if so Thank You again and in closing I think my advice to you would be to take the wait and see attitude for another year or two and see what the market has to offer. I have an idea that within the next few years some amazing things will be coming onto the market that you may want to get in on at that point, soooo as long as you aren't having issues with your unit or the service you get from the office, I think I would ride it out for awhile!