Not sure what engine they are using that is 27HP other than the Kohler. Their website shows an FX730 Kawasaki which was rated at 26HP under the old system and is 24.5 under the new system. Unless there are some models not on the site.
The Wildcat and Tigercat are the same exact mower. The Wild just had some extras tossed in. Hydro cooler, adjustable control levers, flat free front tires. I forget what else.
If you do decide to go with a collection system, I think you will be alright since the Tigercat has 10cc pumps.