When it comes to NV wines, producers want you to think that the wine is the same from year to year and they try hard to make it consistent, but the only thing consistent from year to year IMO is a style. Every producer has a style. With larger producers and many non-family owned smaller ones, it tends to be a consistent one that is influenced by the vineyard team and winemakers, but a common thread is always there. With many smaller wineries especially family owned ones, the style can be more linked to the lead family winemaker/vine grower and can change quite a bit from generation to generation. A few examples of actual producer style change would be JL Vergnon which was very different before Christophe Constant took over the winemaking and vineyards, Hure in Ludes where Francois Hure has revolutioned things, and Selosse where Anselme changed things a lot from what his father Jacques did. Still, in each of these cases there is a consistent style. It may change when someone leaves or a new generation comes in, but consistency is likely going to be there for decades.
The more land you own, grapes you have access to, or reserve wines you have, the more options you have, but each blend of a NV wine is its own animal that is unique just like each vintage wine is unique. More than trying to make the wine taste the same from year to year, large producers are trying to capture a style or feeling with the NV. With Roederer it is finesse filled, zesty, lively, mineral laced Pinot Noir. Clicquot is about fuller, dough, fruit salad. Krug is spicy, slightly nutty elegance with red fruits. Pierre Peters is bright, juicy citrus, cream, and electric minerality. Chartogne Taillet is fuller, bready, tropical fruit. Jacquesson is lean, precise, saline, citrus, and mineral kissed by touches of apple pie and cinnamon.
These styles are consistent from year to year though some years may bring out more of one element than another and do a better job of expressing the style. Jacquesson’s 7xx series is no different from any other NV except that they tell you what is in the bottle. The house style is still there from year to year. Almost all producers worth noting change the grape ratio, vineyards used, and reserves used from year to year. The best also play with different aging vessels, malolactic, growing techniques, dosage, and more. Jacquesson does play with a lot of these variables, but not even as many as Roederer and Clicquot do. Also, just like Jacquesson, big guys like Roederer and Clicquot try to produce the best NV they can each year while capturing the style of the house. Selosse, Margaine, Vilmart, Laherte, Bereche, etc… all do this too. Off the top of my head, I can’t think of anyone who throws out the rule book each year and just does whatever they want to the NV. I can think of a few cases where wines came off this way, but not intentionally.
One of my disappointments or let downs with the 7xx range is that Jacquesson billed it as and still bills it as a a unique, different approach to NVs where each year is a different beast. Each year is different, but the house style is very strong and this no different at Jacquesson than at most other producers. I actually think Krug does a better job of having the Grande Cuvee change from year to year than Jacquesson does with the 7xx series, but, again, that is my personal opinion.
As to the other wines, you mention, which 1988 did you have, the Perfection (basic vintage), Signature, DT? I’m a big fan of the Signature, but not that big on the DT version of the Signature or the Perfection. The DT Version of the Signature is just weird and the Perfection was not much better than the regular NV Perfection.
The 1997 Rose is actually one of the wines of the “new” Jacquesson which to me began with some of the later disgorgements of the 1995 Signature that coincided with the release of the 728. I do/did like the 1997 Rose though I think it was best on its release and a couple years after.