Cant Decide: A.O. Smith Gas condensing WH vs. Indirect fired w/my notsogreen boiler.

Hello folks, this is my first time posting here. Im trying to make a decision based on my budget and my current situation. I just moved into my home 5 months ago. I had my domestic hot water and heating system inspected by a licensed plumer and my current water heater (16yr old natural gas State tank) needs to be replaced ASAP. I started looking into hot water heaters and learned a bit by searching.  Im currently debating on an A.O. Smith Vertex 100 gas condensing unit with 96% efficiency or a triangle tube smart-80 Indirect storage tank hooked up to my current boiler.

I opened the front hood on my boiler.. my home is currently being heated by a Burnham P204-W Natural Gas model 70K btu. This model was built in 1983 and from what I gathered on the Burnham site, it carries a roughly 82% efficiency rating.

I cannot afford to swap out my current boiler with a more efficient model so it will need to stay. Should I get the ao smith model which will run me roughly $2600 installed by a friend of mine which is a licensed plumber in the state and is giving me a deal?

 Or should I go with an indirect storage tank which will run me roughly the same installed, maybe a bit more?

Most say the way to go is indirect fired, but most of the people posting are using this method with a greener more efficient boiler. The indirect has a lifetime warranty on the tank with minimal cost to swap over to a new boiler down the road. The ao smith will need to be replaced in roughly 6 years or so.

Any help is appriciated. Sorry for any newb postings.