Only you can determine your personal desire to continue serving, and how willing you are to mobilize if necessary. Some things to consider related to a drilling while at a regional...
Family situation: If you have a family, you will be gone 50-90% of the time depending on where you live, where you are based, and your seniority. If the reserves require additional time away from home, that could be bad.
Location of unit: If you can drill with a unit near your home, the reserves can actually be a QOL plus...my unit is 5 miles from home, so it gets home a few more days each month (at least I'm home in the evenings).
Rank and time served: If you're somewhat senior, the pay might be equal to or better than regional pay. You normally drop a few days of flying to drill, so if you're very junior you might lose more regional pay than you get from drilling.
Retirement: Your chances of getting a pension-style airline retirement are very low...a small military reserve retirement might come in handy. The more active duty time you have, the larger the reserve retirement will be....if you have 10+ years of active duty, you probably want to at least run the numbers and see what you'll get if you finish out in the reserves.
Networking: You didn't say what branch...if you're AF and can get into a flying ANF/USAF reserve unit you will likely meet pilots who fly for major airlines...this could be a great help in getting beyond the regionals. A non-flying unit will also probably have some pilots. Even if you're not AF, you can probably transfer into the ANG, depending on rank and specialty.
Seniority: If you are mobilized (voluntary or otherwise), your seniority accrues while you are gone...you can leave as a reserve FO and come back as a lineholder or a CA.
Scheduling military reserves with an airline is a non-event...you typically send an email or fill out a form, and they adjust your schedule. You are a commodity and can be easily replaced. You are unlikely to ever get hassled by an airline (other civilian employers are much more likely to mistreat a reservist).