I have recently filled in a typically flawed survey form regarding the old search function. "Improvements" to your search engine will be fruitless unless the problems with your transcription service are resolved. For example; the 'London, England, Electoral Registers, 1832-1965' should be a resource second only to the Censuses, but the transcriptions seem to have been done by a machine working across the pages while the data was recorded in 2 or 3 columns. Consequently, if you enter 'register of electors' into the Street Address box you get nearly 10,000 matches! Enter only 'register' and the matches approach a quarter of a million!! All of these will be invisible to a search engine looking for their real address however much you improve it.
Apparently only 2% of subscribers use the Old Search. How many of us are long time subscribers? It is apparent to me that there are a vast number of people who start their trees, using the New Search as they must, and give up within days because of the bewildering array of nonsensical matches with which they are presented.
I am unable to assess your latest version as I do not use Firefox, but if my experience of the new viewer is anything to go by (slow to load and often freezes) I will be disappointed and very likely to move my subscription elsewhere.