I have a 4 wheel and it also has a real sliding valve, same as my TT. Been using it successfully for over 10 years now. Replaced the wheels once, and have run the thing (probably) over a thousand miles now (and I'm not kidding).
One thing YOU DO WANT is a tote that is big enough to hold ALL the contents of your tanks in one shot!
for example, if you're largest holding tank is 30 gallons, get a 32 gallon tote. There is nothing worse than trying to stop draining a large holding tank into a small tote, and then have the small tote over fill. First time you do this, you'll kick yourself so hard you'll lay yourself up in the hospital! Whether that be a 2 wheel or a 4 wheel tote, get the biggest one you can get.... YOU WILL NOT REGRET IT, especially if you REALLY plan on using it much.
Mine is a Barker 32 gallon, which has always been great for all my campers, as the largest tank I've ever had was 30 gallons. I made the mistake (very early in my experience) to dump both the black and gray at the same time (60 gallons combined), not thinking ... what a heck of a mess. That was way-way-way back "when" ... but it taught me an important lesson.
Only 1 tank at a time, and the tote is ALWAYS bigger than the holding tank!
Not a problem at all after that horrid event ... which I shall NEVER forget!