i find the comments on brass track to be interesting.......
i have found that on dcc the brass track actually ran cleaner than the nickel silver. perhaps dcc has an ultrasonic cleaning effect on brass but not nickel silver? at any rate, even if you decide to go with nickel silver, which i think is a good investment anyway, you can use your brass track for sidings and yard tracks where your locomotives most likely won't venture.
does your brass track have fiber ties? if so, you may run into problems with the rails staying in guage. definitely replace any fiber tie track.
there is a third option of steel track. this will rust on you, and is very hard to solder to, much worse than either brass or nickel silver.
depending on how old your brass locomotives are, they are probably marghinal runners at best, especially if they have the old open frame motors. those motors also have a high current draw. if you convert them to dcc you may have to use a higher current (O scalemaybe) decoder, in addition to whatever modifications you may have to do to the locomotives. you might want to consider replacing these motors with a can type with a low current draw, at the same time you are isolating the motor from the frame in your locomotive.
as for scale couplers, i don't like them. sure they look good, but they tend to come uncoupled easier on rough track. better to use a srandard size knuckle coupler such as a kadee #5 or #148. since most new rolling stock comes with knuckle couplers i usually retain these unless they fail. any replacements i do are kadee which are metal and alot stronger than the other plastic types.
as for dcc systems, after much research i am using the zephyr by digitrax. i was impressed by most of the entry level systems capabilities. nce in particular has customer support second to none in the model railroad industry. but the digitrax unit i am using has the unique ability to use your existing dc power packs as additional throttles. i wish other manufacturers woudl realize how much of a selling point that is. for under $200 you can convert your dc layout into a 3 cab dcc system. other systems need dcc throttles for additional cabs at about $100 a pop.
i have found that on dcc the brass track actually ran cleaner than the nickel silver. perhaps dcc has an ultrasonic cleaning effect on brass but not nickel silver? at any rate, even if you decide to go with nickel silver, which i think is a good investment anyway, you can use your brass track for sidings and yard tracks where your locomotives most likely won't venture.
does your brass track have fiber ties? if so, you may run into problems with the rails staying in guage. definitely replace any fiber tie track.
there is a third option of steel track. this will rust on you, and is very hard to solder to, much worse than either brass or nickel silver.
depending on how old your brass locomotives are, they are probably marghinal runners at best, especially if they have the old open frame motors. those motors also have a high current draw. if you convert them to dcc you may have to use a higher current (O scalemaybe) decoder, in addition to whatever modifications you may have to do to the locomotives. you might want to consider replacing these motors with a can type with a low current draw, at the same time you are isolating the motor from the frame in your locomotive.
as for scale couplers, i don't like them. sure they look good, but they tend to come uncoupled easier on rough track. better to use a srandard size knuckle coupler such as a kadee #5 or #148. since most new rolling stock comes with knuckle couplers i usually retain these unless they fail. any replacements i do are kadee which are metal and alot stronger than the other plastic types.
as for dcc systems, after much research i am using the zephyr by digitrax. i was impressed by most of the entry level systems capabilities. nce in particular has customer support second to none in the model railroad industry. but the digitrax unit i am using has the unique ability to use your existing dc power packs as additional throttles. i wish other manufacturers woudl realize how much of a selling point that is. for under $200 you can convert your dc layout into a 3 cab dcc system. other systems need dcc throttles for additional cabs at about $100 a pop.