The phrase "are often substantially more" is correct and usable in written English.
It can be used when comparing quantities, qualities, or characteristics that are significantly greater in one context than another.
Example: "The costs of living in urban areas are often substantially more than those in rural regions."
Alternatives: "are frequently considerably more" or "are typically much more".
A large body of research suggests that immigrants are often substantially more productive and healthier than both natives in their host countries and non-migrators remaining in their countries of origin (e.g. Chiswick, [1978]; Borjas, [1985], [1995]; Park et al., [2009]; Antecol and Bedard, [2006]; Kennedy et al., [2006]).
Experience has demonstrated that fully specified LOINC terms are often substantially more granular than criteria specified in surveillance case definitions.
In some of the conflicts that seem outwardly to have been mere skirmishes among rivals there is often substantially more at stake.
It is notable that GC-MS volume requirements are often substantially less than NMR, making GC-MS a more powerful approach to doing metabolomics with volume-limited samples.
Run rates are often substantially higher than in the 'golden years' of cricket.
Clicking a button takes the shopper to a list of individuals and dealers whose prices are often substantially lower.
Cities are often substantially warmer than their surrounding rural areas.
Another is that the value of the deposit is often substantially larger than the amount invested.
A strength of the computational screen was its prioritization of potent molecules, often substantially more so than those found empirically, and its ability to highlight chemotypes unexplored empirically.
And while banks were willing to make mortgage loans for more than the value of the house before the credit crisis, buyers now find they must put up at least 10 percent, and often substantially more.
Although older films are often more glaringly exasperating in terms of on-screen representation, both Brown and Goerz are dubious of whether film is substantially more diverse today.
