Several years ago I had an SPT2422 2-dog system and liked the features of the collar. The only negative I found was the size of the buttons on the transmitter made it difficult to use with gloves on .... and that does become an issue up here in the winter months ..... so went back to a TT Pro 100.
2 is going be my limit, I have a hard enought time with 2.
Ended up going with a Tri Tronic Flyway. With the rebates they have it made it a bit easier to spend a little more (as apposed to a lot without the rebate )