The scoop on AFUE ratings is this - AFUE was developed for warm air furnaces, not hot water or steam boilers. The cycle of operation is different so results will be different. AFUE on hot water boilers uses artificially low boiler temperatures, less combustion air than is safe to use in real life, does not consider draft regulator losses, or residual heat remaining in the boiler when the heat call is done. Less combustion air equates to lower stack temp. Boiler temp is set to run at 120-140ú with sufficient load to keep the burner running steadily. Draft regulators take some house air up the chimney with the flue gases and so on.

Real life situations and feed back from dealers and customers back up Energy Kinetics' claims to fuel savings. In addition, impartial testing was done within the past few years at Brookhaven National Labs comparing the various types of oil and gas boilers currently being sold in the US. System 2000 came out on top.

Who am I? A satisfied System 2000 owner.

you don't happen to have a link to the BNL research do you?

Both units are good quality, but the Buderus is a 3-pass boiler, and 3-pass boilers are usually a little more efficient than the pin-style boilers like the V8 you mentioned.
If you want to compare apples to apples look that the MPO from Burnham, which is also a 3-pass boiler with 87% efficiency. It's a very nice running unit, and should match up well with the G115. The MPO has some features that G115's don't include, and it is made with some impressive-looking castings. My experience has been that the MPO's are easy to install, the combustion is excellent, and it's easy to clean and service - which helps keep them running efficiently. Oil burner set-up is important, because it has a big effect on how efficiently the boiler heats.
I've been in the heating business for about 15 years, and worked on both of the units you mentioned - they're both good boilers. But for the dollar for dollar, I think the MPO's are simpler and do more for the $ especially since the IQ reset cards can be added to them.
The V8, it's a good option if you have a tankless heater for making hot water in the boiler. The efficiency isn't as high as the MPO, but the quality is very good - the cracking issue was fixed about 10 years ago. I also like the fact that that Burnham's are still made in PA - not imported. Do some research, but you're probablly on the right track.

Fritzgarden, http://www.bnl.gov/est/files/pdf/ButcherAachenPaper.pdf should take you there. System 2000 has some easier to understand charts and explanations on their website, www.energykinetics.com. In the Brookhaven article System 2000 is system #3

I went through this same decision a year ago.

I looked at MPO from Burnham and the V8 series, Buderus G115WS with Logamatic 2107 and System 2000.

My final decision was the Buderus...because I couldn't find a bad thing said about them. I have read/heard about issues with Burnham and incidences with cracking cast iron (like heating_pro mentioned). I also heard that Burnham did not stand behind their product when this happened and a lot of customers were left in the lurch.

I wanted a boiler that would stand up to time and a company that would stand behind their product.

I love this boiler (and matching indirect hot water tank).
I've already seen the savings in oil usage (I just got a delivery Oct 26,2010 and that should last until Jan 2011 and even then I'll only be at half a tank).

I would highly recommend the Buderus with Logamatic 2107 controller (and matching indirect hot water tank if you need a water tank).

It's a beautiful system and it's quality is top notch.

P.S. The Buderus just had it's first yearly cleaning and the thing was spotless inside.
Also I would recomend the Riello burner to go with the Buderus boiler.

Let us know how you make out with whatever decision you make.

Zeroing in on the Buderus 115 3 section...

One installer says only use a Beckett burner, the other swears by Carlin. Which one?

Neither says we'd need to line the chimney. Buderus phone support recommends a chimney always be lined. It's in the center of the two story 1870's house and in typical shape for it's age; can we get by without relining?

We'll be keeping the existing gas hot water heater for now. Should any provisions be installed now for adding a tank to the Buderus later?

We'll also be keeping a Intellicon HW+ and using it instead of the outdoor control. Wise decision?

Lastly, any caveats about the install we should be aware of?

Thanks.