Making generalizations doesn't seem a good idea on this forum. That being said, I will publicly state that I had a PERSONAL issue with the Salters a long time ago, vowed to NEVER buy another plant from them and haven't ( since 1999 or somewhere around that time)Back then, I bought entire collections year after year as some of you do now. In part I blamed myself for my stupidity in buying an expensive introduction that turned out to be one they hadn't registered. The name was later changed ( years later when it was finally registered) and I learned an expensive lesson. If registration matters to you, always, ALWAYS, check before you buy a plant!!! While registration matters a lot to me, it may not matter much ( or at all) to anyone else. IMHO, selling a plant purported to be registered that isn't is selling a glorified seedling that has no name protection (in other words, someone else can register a different plant and use the same exact name if it is not name protected) it can never be entered into a show etc. So that is my personal issue and likely not a valid reason for not buying for some of you, but it is my choice, as it is for any of you to choose who to buy from. Caveat Emptor. I still love Liz Salter's small/ minis, but some have been tender here and I always use secondary sources if there's one that I "must have."
I do grow some Florida, TX, and LA plants but grow a heck of a lot fewer of them than what was here 10 or 20 years ago. Over time, plants bred in these areas do not seem to do as well in my garden, but that is a personal observation from my garden. I've seen plants from these areas grow and do well in other club members gardens. There are micro-climates everywhere. Everybody knows someone who will tell you they plant a known tender plant in their most sheltered garden location!
My philosophy is why would anyone want to buy plants that struggle to bloom or survive or only produce a few blooms annually when over the years plants bred by certain hybridizers have proven over and over to be fabulous garden plants here ? Every so often I take a chance on FL evergreens ( got a few from Karen Pierce a couple of years ago and they have survived and done well, but last winter was fairly mild. Karen Pierce has been a very accomodating and pleasant seller and I'd buy from Floyd Cove again but in the spring not fall) Hybridizers such as Margo Reed and Jim Murphy (Woodhenge) or Judy Davisson (NC) produce plants that are as hardy as weeds here, plus they're beautiful. It helps that their gardens are geographically near too plus IMHO they are extremely ethical / honest hybridizers and that ( also a personal issue) is important too, IMHO. Other growers whose plants do well here, just off the top of my head - are: Sandy Holmes /Mike Holmes ( OH), Nan Ripley( IA), Karol Emmerich (MN), George Doorakian (MS); Ellen LaPrise(MS); Bret Clement(IN) and Jamie Gossard's (OH) plants have all done very well here - although a caveat. Sometimes new intros from Jamie have been on the really small side and I've lost a few, so I prefer to wait a couple of years and if there's something that's really a "must have," find a secondary source. Tim Herrington's plants do extremely well here, as do Scott Elliotts. Both are in GA, but plants seem to like it here. Last year I tried a few new intros from the Singletarys (GA) and hope they prove to be hardy, as I like their plants a lot and will probably be tempted again!
Nowadays I tend to avoid plants from Petit gardens, as some have proven tender here. I love the look of Luddy's ( Lambertson) 's plants but some of the newer ones have been iffy here too. Bottom line, many experienced growers I know will wait a couple of years, then purchase from secondary sources closer to their home if they are interested in a plant from a zone much different than theirs, the assumption being that the plant has survived in an environment more similar. If in doubt, ask the seller about hardiness. If they tell you they don't know, it's your risk!
JMHO.