Did you find a solution to this? I have upgraded the lucene jars to 2.9.1 to solve another probelem and everything still seems to work successfully so that should be possible if you want/need to upgrade.
Hi, while Lucene 2.9 aims to be drop-in compatible with 2.4 it will break the use of filters; so you can do it as long as you don't enable multiple filters.
Lucene 2.9 is not having native numeric handling, it's always about strings, but it applies some nice tricks which speed things up a bit, like splitting up a high precision number in several fields: you can do the same thing like splitting the integer part from the real part of the string, or add a separate part for the thousands, something like
12.3 -> th un cent
Of course that makes querying more complex, and that's what the new Lucene does - of course for the full and exact explanation please see the lucene forums.
Current trunk of Hibernate Search is working fine on Lucene 2.9 but is not making full use of this feature yet; it should do before the GA, but it will require Hibernate 3.5 so it might now work with current Seam.