I have a 18 year old Tetco 5 ton split system running in open loop (pump and dump) that just crapped out. Looking at replacing unit with a Mega-Tek, GeoComfort, or Econar 5 ton self contained unit. Seems to me they all use the same compressor Copeland scroll 2 stage, same ECM fan motor, GE and same heat exchanger copper or cupronickle. Circuit boards seem to be the only thing that is unique. Anybody had any positive or negative experience with any of these units. This gothermal stuff seems like a crap shoot. Lots of different brand names made by the same manufacture.

The key is a good installer who knows his equipment and Geothermal.
The forums are filled with stories about installers who don't.

I would get lots of quotes, then of the best ones, check the installers references, certification, training, etc. The most expensive company isn't always the best, and the least expensive company isn't necessarily the worst. We were fortunate and found the best installer (a tie between two) had the lowest price.

Will a packaged unit work in your application (you said you currently have a split system)?

Have you considered Water Furnace? Our split and packaged systems have been working great in the first 8 months of use. I suggest a long (10 year) warranty on any system you get. Safer that way.

Use the search feature of this site to find threads about the equipment you mentioned.