Disadvantage in url rewrite

[joe2]

I have written in my .htaccess

RewriteEngine on
Options +FollowSymlinks
RewriteBase /
RewriteRule ^{a/(.)/(.).html} /a.php?x=$1&y=$2

It is working fine. Is there any disadvantage in using URL Rewrite in anu manner (server side, script side, search engine side).

Thanks in advance.

[stolzyboy]

for a short simple answer... NO

not that I am aware of anyway

[joe2]

Thanks a lot..